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GEOLOGY AND PALEONTOLOGY.
The Limestones of the Jenny Jump Mountains, New Jersey.-Accompanying the report on the Archean Geology of New Jersey, by Mr. J. E. Wolff is a paper by. Mr. L. G. Westgate on the Geology of Jenny Jump Mountain, chiefly interesting on account of the conclusions reached by the author concerning the crystalline limestones of that region.
The area under consideration embraces the northern half of Jenny Jump mountain in Warren county, New Jersey. This mountains lies along the northwestern border of the bigbland area, and is a sort of outlier or peninsula reaching into the later Paleozoic rocks. The main ridge of the mountain consists of gneisses; the limestone occurs at its extreme northeastern end, with outcrops along the southeast border of the mountain.
The author discusses in detail the position, lithology and relations to the crystalline limestones in other parts of New Jersey, and reviews the views of previous writers as to the age of the Sussex county limestone, which has generally been considered the type and representative of other localities. Mr. Westgate's views are given in the following summary :
“The crystalline limestones of Warren county are believed to be distinct from and older than the blue magnesian limestone of Cambrian age, which occurs along the northwestern side of the New Jersey Highlands. They are believed to be distinct, for the following reasons."
“1. They differ lithologically from the blue limestone in being thoroughly crystalline, and in containing large amounts of accessory metamorphic minerals.”
“2. They are intimately associated with and apparently interbedded with the older gneisses; and gneisses occur also interbedded in the limestone."
“3. They show no intimate association in areal distribution with the blue limestone, nor any tendency to grade into it."
“ 4. The metamorphic changes to which the white limestones bare been subjected are general in their nature, and are not due to the action of the eruptives by which they are cut; so that no sufficient agent is at hand to account for the supposed change from blue into white limestone."
“ The white limestones are believed be older than the blue Cambrian limestone, because (1) they occur in intimate association with the gneisses which are of admitted pre-Cambrian age, and because (2) they have been subjected to general metamorphic forces resulting in great changes, of which the neighboring blue limestone shows no traces.
"That the other crystalline limestones of New Jersey are of the same age as those of Warren county, has not been proved. The theory bas generally been that they are. If they are, and if the position taken in the present paper is valid, then the crystalline limestones of Sussex county, and of other places in New Jersey, would also be, as they have generally been supposed to be, of pre-Cambrian or Archean age.” (Ann. Rept., New Jersey State Geologist for 1895. Trenton, 1896.)
Unios from the Trias.-Four new Triassic Unios are described by Mr. C. T. Simpson. The collection of which they form a part was obtained from the Dockum beds, a formation underlying the Staked Plains of Texas. Taken as a whole, these Unios closely resemble in form, and are apparently nearly related to those of the Jurassic beds of North America, while 3 of the species bring to mind most strongly the species which now inbabit Europe and western Asia, and a small group belonging to the Mississippi area. The variety of characters displayed by these Triassic Unios go to show that the genus must have been well established at the time the Dockum beds were laid down, thus tending to overthrow Neumayer's theory that the Unionidæ were derived from the genus Trigonia, which probably does not date back to a period earlier than that of the shells under consideration. (Proceeds. U.S. Natl. Mus., Vol. XVIII, 1895.)
The Cadurcotherium.-M. Boule calls attention to the recent discovery of the lower jaw of a Cadurcotherium (Gerv.) at Barlière (Haut-Loire). The specimen denotes an animal of the size of a small rhinoceros. It was found in oligocene arkoses associated with a fine mandible of Elotherium magnum, and fragments of Aceratherium, and the remains of turtles. Until now Cadurcotherium has been represented by isolated teeth and fragments of mandibles. The new find is important, showing the animal to be unique among its contemporaries. It presents certain resemblances to South American types--noticably Astrapotherium of the Patagonian Eocene, but is, according to Osborn really related to the rhinocerontic genus Metamynodon.
Notes on the Fossil Mammalia of Europe, V-The Phylogeny of Anoplotherium.—The early attempts at the construction of a phylogeny of the even-toed ungulates, included the genus Anoplotherium, which was considered by Paleontologists of twenty-five years ago, as a primitive form, especially in its foot structure, Anoplotherium certainly possesses a number of primitive characters in its manus and pes, such as the separation of the metatarsals, and the non-fusion of the podial elements, but the inadaptive reduction of its digits, as pointed out by Kowalevsky and the peculiar position of the pollux and hallux, excludes the possibility of placing Anoplotherium in the direct line leading to any of the living Artiodactyla.
I propose in this short paper to attempt to prove, that Anoplotherium has been probably derived from Dacrytherium, a closely allied genus, but whose foot structure is normal and which resembles that of many of the early Eocene Artiodactyla such as Cainotherium. Prof Cope' suggested that Cebocharus may have been the ancestor of Anoplotherium, but the structure of the skull in Cebochorus, is already quite modernized, nearly as much so as in the true pigs, consequently I am inclined to think that we shall have to look for some other form as ancestral to Anoplotherium.
The general form of the skull in Dacrytherium is like that of Anoplotherium, however, in Dacrytherium there is a strongly pronounced preorbital fossa, which is absent in Anoplotherium. The crowns of the upper teeth in Dacrytherium are low and primitive in structure. Ther exhibit rounded external crescents, which are not at all angular. Anoplotherium, especially the large species, the crowns of the superior true molars are more lengthened than in Dacrytherium and the external crescents are angular and broad. We see this change in many mammalian phyla from extremely low crowned molars, to those which are tending to the hypselodont condition. As regards the intermediate stage, between Dacrytherium and Anoplotherium, as to the height of the molars, this is found in the genus Diplobune.
The lower true molars of Dacrytherium exhibit two internal cones, which is the normal number in the Artiodactyla. It is interesting to record, that I have noticed in a number of young jaws of Dacrytherium in which the true molars were just coming through, that the anterointernal cusp, which is single in the adult, shows a slight reduplication, which is the normal condition in Diplobune. The division of the metaconid is carried still further in the largest species of Anoplotherium, although I have examined many jaws from the Phosphorites of the Anoplotherium, and I can confidently state, that all gradations exist between the complete isolation of the two antero-internal cusps of the typical forms of Anoplotherium, and the single condition of these cusps, * Artiodactyla, AMERICAN NATURALIST, Dec.,
which is found in the supposed ancestral genus, Dacrytherium. Accordingly I am not acquainted with any good generic character at present, which will distinguish the so-called genus Diplobune from Anoplotherium, as in many cases in jaws from the Phosphorites, it is impossible to say whether they belong to Anoplotherium or Diplobune. Dr. Henri Filhol informed me that he was of the same opinion, in regard to the validity of the genus Diplobune.
In Dacrytherium the hind foot has at least four well developed toes and the internal digit is not placed at an angle with the others as in Anoplotherium. This structure of the pes is just what one would expect to find in a genus standing in ancestral relationship to the more specialized members of the Anoplotheriide. Granting that Dacrytherium fulfills in most of its characters, what we require of a form, supposed to be ancestral to Anoplotherium, there is still the presence in Dacry. therium of a preorbital fossa, which is absent in the skull of Anoplotherium, and also another objection, is, that Dacrytherium has claw-like ungual phalanges, much as in Agriochorus. I believe, however, the extremely compressed ungual phalanges of Dacrytherium is of little weight against this genus being ancestral to Anoplotherium, for in the latter these phalanges are rather compressed, more so than in the normal Artiodactyles, and they could be easily derived from those of Dacrytherium. The structure of the skull is not known in all the species of Anoplotherium, and one of them may have had a skull with a preorbital fossa, which is so characteristic of Dacrytherium.
As is well known, the original specimens of the manus and pes of Anoplotherium commune, which are in the Muséum d'Histoire Naturelle, Paris, show only two well developed digits as restored by Cuvier. This restoration of the feet of Anoplotherium is shown by Schlosser and Zittell to have been an error on the part of Cuvier, and I quite agree with these authors on this point. Prof. Zittell in his “ Traité de Palæontologie” in speaking of the structure of the feet in Anoplotherium remarks “La plupart des représentation de la patte d'Anoplotherium faites jusqus à present omettent par erreur à la patte antérieur l'index et le rudiment de pouce, à la patte postérieur le second doigt.” I have examined a fine cast of the hind foot of Anoplotherium commune and I find that the restoration of the internal portion as completed by Cuvier is quite erroneous. The two small bones placed by him on the tibular side of the pes do not at all fit the facets on which they are placed. The broad and obliquely placed facet on Mt. 111 in A. commune is for the large and wide spreading second digit, this same structure of the metatarsal occurs in A. (Eurytherium) latipes of the upper Eocene of Dé. bruge.
Summing up the principal changes which have occured in the evolution of Anoplotherium from Dacrytherium, I emphasize the following: 1. Increase in height of the crowns of the upper molars, and the reduplication of the metaconid of the lower molars, this division of the metaconid is found in an incipient conditiou in young jaws of Dacrytherium. Complete separation of the metaconid into two distinct cusps only occurs in some forms of Anoplotherium. 2. The hind foot of Dacrytherium is normal in structure, and has at least four toes, this is the primitive type of pes, from which the specialized foot of Anoplotherium has been derived.
Note.-In my “Notes on the Fossil Mammalia of Europe,” part III, AMERICAN NATURALIST, April, 1896, I find two mistakes, which should be corrected. On page 309, third and fifth lines from top, read Adriotherium, instead of Adiotherium as printed, and also page 310, eighth line from the bottom, read Anoplotheriide, in place of Suillines. -CHARLES EARLE.
De Toni's Sylloge Algarum.-Dr. De Toni' has recently issued the third volume of his Sylloge Algarum. It deals entirely with the Brown Algæ or Phæophyceæ--the FUCOIDEÆ as he calls them. A thousand species are described under one hundred and eighty genera, which are grouped into twenty-nine families. He divides the group into three orders, Cyclosporinæ, (Fucacea) Tetrasporinæ (Dictyotex) Phæozoosporine (Phæuzoosporeze).
Splanchnidium rugosum the interesting plant which after careful study was placed by M. O. Mitchell and F. G. Whiting in the Pheosporinæ, is retained in the Durvilleacea, the fruit being described as a polysporous oogone. The general appearance of the plant and the structure of the conceptacles suggest a close relationship with the fucoids, but if the above investigations are to be accepted the plant
Edited by Prof. C. E. Bessey, University of Nebraska, Lincoln, Nebraska. 2 Sylloge Algarum Omnium Hucusque cognitarum by J. Bapt. De Toni, Vol. III, Fucoidea.
3 On Splanchnidium rugosum Grev. the type of a new order of Algæ, Phycological Memoirs, Pt. I, I., 1892.