case of Belodon buceros. Although there is no parietal foramen of the skull, the epiphysis is so enormous as to lead to the belief that the pineal eye was present. It had communication with the orbit by a canal on each side, which Professor Cope calls the orbitopineal canal.

TERTIARY.-Lydekker recently described Scelidotherium chilense, from Tarapaca, Chili. It is characterized by extremely short nasals. He also described as new S. bravardi, from the Argentine Republic, a form which had previously been included by Owen with the typical S. leptocephalum.

POSTPLIOCENE-The discovery at Spy, in the Belgian province of Namur, of remains of two human individuals allied to those before found at Canstadt and Neanderthal, has proved that this. type of man is that of a race which lived in the age of the mammoth, the bones of which, along with those of the rhinoceros, hyæna, cave-lion and cave-bear, etc., were also found in the Spy cavern. The two skulls serve as a sort of link between the Neanderthal skull and others of the same type, which can thus be traced from Stængenes, in Scandinavia, to Olmo, in Italy. The men of Spy are described by M. Fraipont, who has made an exhaustive study of the remains, as a short, but thick-set, robust folk, walking knees foremost and bandy-legged, like the modern Lapps. The broad shoulders carried a long, narrow, and depressed head, with very prominent superciliary arches, high cheek-bones, enormous orbits, retreating brow, and receding chin,—a combination of characters not to be found in any living race, and in many points showing apian affinities.

MINERALOGY AND PETROGRAPHY.

Petrographical News.-In the August number of the Geological Magazine Mr. J. J. H. Teall describes an interesting suite of hornblende rocks which occur as intrusive sheets and bosses in the limestones and quartzites of the Assynt district in Scotland. From the description which the author gives of them, these rocks appear to be somewhat similar to the camptonite of Dr. Hawes,3 Three types are distinguished,-viz., hornblende porphyrites, diorites, and porphyrite diorites. In the last two classes hornblende is abundant in well-formed porphyritic crystals, bounded by the planes ∞, ∞P, -P and oP. Some of the larger of these crystals are so perfectly developed that when separated from the surrounding rock-mass their angles can be measured with a contact goniometer. Most of them are twinned according to the ordinary law, and many present fine instances of zonal Edited by Dr. W. S. BAYLEY, Madison, Wisconsin.

2 Geol. Magazine, August, 1886, p. 346.

3 Lithology of New Hampshire, p. 160, et seq.; Rosenbusch's Massige Gesteine, 1886, p. 333.

growths. In the hornblende porphyrites the hornblende crystals are less abundant. This class is characterized by the presence of feldspar in two generations. The porphyritic crystals are sharply outlined, and are developed in thick tables parallel to the clinopinacoid. They often show zonal banding, due to the variations in the optical characteristics of successive layers. The feldspar of the second consolidation occurs in grains, often forming the greater part of the ground-mass in which the crystals of hornblende and feldspar are found. In addition to these minerals, a very light-colored pyroxene is present in those sheets which are intrusive between limestone.- The same author 1 mentions another instance of the development in eruptive rocks of a schistose structure, accompanied, at the same time, by a change in mineralogical composition. The normal gabbro of the Lizard peninsula in Cornwall is intrusive in serpentine and other rocks, and is itself penetrated by dykes of epidiorite. It is composed of diallage, hornblende, and saussuritized plagioclase, with here and there a little fresh olivine. The hornblende is secondary and of three varieties,—a compact brown, a uralitic, and an actinolitic variety. The saussuritization of the plagioclase and the alteration of the original augite into hornblende appear to increase as the pressure to which the rock-mass was subjected is seen to have been greater. Generally, though not always, the alteration in the composition of the rock is accompanied by a change in its structure. The massive character of the normal rock is lost, and a secondary schistose structure takes its place. These schistose rocks the author calls flaser-gabbros, augen-gabbros, and gabbroschists. In the first the parallel arrangement of the constituents is distinct, but not so marked as to give rise to that perfect fissility characteristic of the third class. The augen-gabbros àre similar in structure to the well-known augen-gneisses. These different types of structure, as well as the alteration in the original composition of the rock, the author regards as results of the action of pressure, which in some cases was so great as to give rise to faults. -The hyperesthene crystals from the hyperesthene andesite of Pokhausz, Hungary, have been isolated and examined by A. Schmidt.3 The rock in which they occur consists of a dark gray isotropic ground-mass, in which the hyperesthene and plagioclase are scattered in porphyritic crystals. The grass-green augite of the amphibole-andesite from near Kremnitz has likewise been isolated and examined. The igneous rocks of the Warwickshire coal-field, according to Professor Rutley, are syenites, andesites (English), quartzites, diorites (both augitic and olivenitic), and tufas.

' Geol. Magazine, November, 1886, p. 481.

2 Cf. American Naturalist, December, 1886, p. 1049.

3 Zeits. f. Krystall., xii. p. 97.

4 Geol. Magazine, December, 1886, p. 557.

Mineralogical News.-In 1871, Tschermak discovered that the optical characteristics of the various pyroxenes depended in great measure upon the proportion of their iron constituent. He found that with increase of iron there was a corresponding increase in the size of the optical angle, and also in the inclination of the acute bisectrix to the vertical axis of the monoclinic varieties. In later years Wiik, Herwig, and Doelter examined monoclinic pyroxenes with the view of deciding as to whether Tschermak's observations would be found to apply generally. Their results, however, were not conclusive. Very recently G. Flink' of Stockholm, declares, as the result of investigations made on diopside, schefferite, and rhodonite, that the crystallographic angle varies. with variation in the percentage of iron, increasing with the increase of this constituent and decreasing with its decrease, but within very small limits (22'). The morphotropic action of manganese is to diminish the size of the angle and to carry the crystallization of the pyroxene over to the triclinic system. The value of this angle for different proportions of manganese is given as follows:

Diopside (Mn=free). Schefferite (MnO8.32 %). Rhodonite (MnO=41.88 %). 74° 11/ 73° 53' 71° 1534' The optical angle and the angle of extinction in the plane of symmetry both increase with the rise in the percentage either of iron or manganese. The geometrical, optical, and chemical properties seem to show that the diopsides among the pyroxenes form a continuous series analagous to the plagioclase series among the feldspars.In the course of the above investigation Flink had occasion to work over a large series of diopside, schefferite, and rhodonite crystals, the results of which he incorporates in his paper. On diopside from Nordmark, Sweden, he finds the following new forms: P5, P7, P∞, -2P∞, -P and P. Schefferite is the name given by Mikaelson to a manganeserich diopside from Långban. According to Flink its composition is:

It crystallizes in red, brown, or black crystals bounded by the planes OP, P, P., 2P, Po, P, and -P. The habit of these is determined by the greater or less development of the three planes op, P, and P. Twins are very common according to the ordinary law of the pyroxenes. The axial ratio is: a:b: c = 1.1006: 1:0.59264. B=73° 53'. In thin section the mineral is almost colorless. It possesses very weak pleochroism. It extinguishes 44° 25%' in the clinopinacoidal section, is positive and 2Va=65° 3' for yellow light. Rhodonite usually occurs massive. But few fine crystals have heretofore been described. In the article under

Zeitschrift f. Kryst., xi. p. 449.

discussion Flink mentions the fact that he has become possessed of a large collection of good crystals from Pajsberg and Långban. These he examines, and finds on them nineteen forms new to the species. The axial ratio as calculated from his measurement is: a:b:c=1.0727:1:0.52104. The inclinations of the axes to each other are a = 76° 41′52′′, B=71° 15′ 15", 781° 39′ 16′′. The plane of the optical axes is inclined to oP and 'P at 63° and 381⁄2° respectively. It corresponds to P16,,PI. The acute bisectrix is perpendicular to the plane PT7 and is probably negative. 2Va=76° 12′ for sodium light and p < absorption b>a>c—. The intergrowth of minerals of analogous composition has within the past few years been proven to be very much more common than was formerly supposed. The microscope has revealed the fact that very many rock-forming minerals, as, for instance, the pyroxenes and the feldspars, very frequently occur intergrown with lamellæ of analogous but slightly different composition. The method of etched figures has shown the same. statements to hold good in regard to minerals which occur only in massive form. By the latter means Baumhauer1 has succeeded in detecting irregular intergrowth of various substances in cloanthite and smaltite. The occurrence of thin lamellæ of ilmenite in crystals of magnetite from the chlorite-schist of Greiner in the Zillerthal, is placed beyond doubt by the separation and analysis of the two components of these crystals by Cathrein.2

-Little bournonite3 crystals cover the cubic faces of galena from Prîbram. Their long axes are either parallel to the combination edge between ∞∞ and O, or they are inclined to this at an angle of 45°.

Crystallographic News.-The twinning law of lepidolite from Schüttenhofen, in Bohemia, is the same as that for the more common micas,-i.e., the twinning plane is P. The dispersion of the axes is very similar to that in the hemihedral crystals of the orthorhombic system. Intergrowths of muscovite and lepidolite take place parallel to the twinning position of micas of the same composition. Several brief communications on the crystallography of topaz have lately appeared. In one H. Bücking 5 discusses the forms appearing in the topaz of Mexico, with reference more particularly to the Durango crystals. A large number of new planes have been detected. A second article, by Fr. Feist, describes a crystal of topaz from the Ilmengebirge.

The Zeitschrift für Krystallographie for the past few months has contained quite a number of short articles descriptive of single

Zeits. f. Kryst., xii. p. 18.

3 C. Hintze, Ib., xi. p. 606.

5 Ib., pp. 424 and 451.

6 Cf. also Des Cloizeaux, Bull. d. 1. Soc. franç. de Min., 1886, p. 135.

7 Zeits. f. Kryst., xii. p. 434.

8

=

crystals of different minerals from various localities. Gehmacher' gives a series of measurements on the faces of colorless zircon crystals from the Pfitschgrund, in the Tyrol. The axial ratio of datholite from the Seisser Alps, as calculated by Riechelmann,2 is ab:c=0.63584: 1:0.6329. The angle — 89° 54′.—The new forms 1P, P, P2, P, P5, and P2 (?) have been added to the list of planes occurring on anatase 3 by Seligmann.-The same investigator has measured pyrrhotite from the druses of basalt from the Cyclopean Islands. The results indicate that the mineral crystallizes in the hexagonal system with the axial ratio: 1:1:1:1.65022. In the same article Seligmann describes a wolframite crystal from the Sierra Almagrera in Spain, on which are the two new forms -2P and -3P. The mineral is monoclinic with the axial angle ß=90° 26' and the axial ratio 0.82144: I: 0.87111.New crystallographic planes have also been discovered by Sansoni on calcite from Blaton, Belgium. Sansoni 5 also mentions the fact of the tendency in barite crystals from Vernasca, Italy, for the prismatic and end faces to converge towards the free end of the axis to which they are parallel, and along which the crystals have their greatest develop

ment.

Miscellaneous.-The diamonds found in the African diamondfields occur in the immediate neighborhood of volcanic pipes cutting carbonaceous strata of Triassic age, and containing as inclusions pieces of the shales forming the greater part of the series, through which they break. The richest yield of the gem is obtained from the outer portion of the pipes, where the included fragments are most abundant. The rock composing the lower portion of the pipes is quite fresh. It is a peridotite of which certain portions are diamantiferous, while other portions contain no diamonds. The diamantiferous variety is crowded with fragments of shale, while the non-diamantiferous variety is free from them. From these and other facts it is concluded that the diamonds are secondary minerals produced by the reaction of the lava (with heat and pressure) on the carbonaceous shales in contact with and enveloped by them. A study of the occurrence of diamonds in other regions seems to indicate the correctness of this conclusion, as Mr. Diller 7 points out the fact that in most American localities where diamonds are known to occur the same relation of carbonaceous shales and very basic eruptive rocks has been observed to exist. Mr. O. A. Derby, on the other hand, does not accept this explanation for the origin of the Zeits. f. Kryst., xii. p. 50. 2 Ib., p. 436. 3 Ib., xi. p. 337.

6 H. C. Lewis, Geol. Magazine, 7 Science, Oct., 1886, p. 392; Geology of Elliott Co., p. 27. 8 Science, Jan., 1887, p. 57.

4 Ib., p. 352.

5 Ib., p. 355. January, 1887, p. 22.

also Geol. Survey of Kentucky; Report on the