liable to be differently understood, and he admits (p. 72) that the placenta, the peculiar character of which he takes for his guide in defining the five groups of the Monodelphia, is "a structure not universally characteristic of the class." With these exceptions and gaps taken into account, in addition to the limitation of the placental characters to one sex, is not the Cerebral system as likely to lead to a natural grouping of the orders of Mammalia as one based on the reproductive organs?

From what we have stated it must not be supposed, by those who have not yet read Prof. Huxley's invaluable résumé of the classification of the Mammalia, that the author has confined himself to considerations resulting from the study of the reproductive organs, for, on the contrary, while their peculiar structure, and the development of the embryo and its relation to the parent, forms the basis of his division of the class into three subclasses, and the structure of the placenta that of the five secondary groups of the principal subclass; he also gives other characters common to each group, and in his summary of the orders he brings together their principal structural elements, and discusses their relations from other stand points, for an understanding of which we must refer the reader to the work itself.

Without farther comments-other than to state that it is our belief that the orders of the birds will require farther confirmation before they are generally adopted by ornithologists, and remarking that the orders of the Reptilia and Amphibia are mainly those now commonly receivedgive the groupings of his second Province, the SAUROPSIDA.

-we

Class I. BIRDS (Aves), he divides into three orders:—(1) SaururÆ, containing only the extinct form, Archæopteryx; (2) RATITE, containing the Ostriches, Emeus, Apteryx, etc.; (3) CARINATE, containing all the ordinary birds.

Class II. REPTILES (Reptilia), he divides into four orders of living and five of fossil forms: -(1) CROCODILIA (Crocodiles, Alligators, and their allies); (2) LACERTILIA (Lizards, Blindworms and Chameleons); (3) OPHIDIA (the Snakes); (4) CHELONIA (the Turtles and Tortoises). The five orders represented only by fossils are the ICHTHYOSAURIA, the PLESIOSAURIA, the DICYNODONTIA, the PTEROSAURIA and the DINOSAURIA.

The third Province, the ICHTHYOPSIDA, containing the classes of Amphibians and Fishes, is arranged as follows:

Class I. AMPHIBIANS (Amphibia). Four orders: -(1) URODELA (the Newts, Salamanders, Sirens, etc.); (2) BATRACHIA (the Frogs and Toads); (3) GYMNOPHIONA (the Cæcilians, etc.); (4) LABYRINTHODONTA (fossil forms).

Class II. FISHES (Pisces). Six orders :-(1) DIPNOI (containing only the singular "Mud fishes," Lepidosiren and Rhinocryptis); (2) ELASMOBRANCHII (Sharks, Skates, and Chimæras); (3) GANOIDEI (Sturgeons, Garpikes, Dogfish (Amia), etc.); (4) TELEOSTEI (the ordinary "Bony" fishes); (5) MARSIPOBRANCHII (Lampreys, etc.); (6) PHARYNGOBRANCHII (represented by the single genus Amphioxus).

In this classification of fishes Prof. Huxley has simply followed the groups of Müller, given twenty-three years ago, but has lowered the rank of the groups from subclasses, as they were considered by Müller, to orders. These groups are undoubtedly well founded, but their equality of rank may be questioned. The Dipnoi are very Amphibian in many of their characters, and the typical Ganoidei are equally Reptilian in some of theirs, both agreeing, however, in much that is important in their anatomy (five out of the eleven characters assigned by Huxley to Dipnoi being common to the Ganoidei as well, and the other six characters are either of an aberrant or embryonic nature). The Elasmobranchii are equally an aberrant group, with affinities to the higher classes of Birds and Mammals. The Marsipobranchii are low, degradational, or embryonic forms, when relatively considered with the other groups of the class; and the single genus of the Pharyngobranchii is of so low an embryonic type that it must be considered as representing a distinct subclass, unless the embryology of the lower Marsipobranchiates shall prove it to be the lowest order of that subclass. The Teleostei are the most fish-like of fishes, agreeing more nearly with the Ganoidei than with the other groups. Are these six groups of equal value? and if so do they rank as subclasses or as orders? and what is the rank of the groups into which all but the Dipnoi and Pharyngobranchii are most naturally subdivided? If the same considerations used to discriminate the orders among Mammals, Reptiles, or Amphibians be applied to the fishes, will not the secondary divisions of the groups Teleostei, Elasmobranchii, Ganoidei and Marsipobranchii by force be considered as orders? On these considerations we agree with Prof. Gill, who in 1861, in a discussion of the subject of the higher groups among fishes (Proc. Philad. Acad Nat. Sci.), united the Dipnoi with the subclass of Ganoids, considering them only of equal rank with his other three orders of the subclass. The Pharyngobranchii, which Prof. Gill considers as an order of the Marsipobranchii, we keep as a distinct subclass, subject to change on farther knowledge of the embryology of the Marsipobranchiates.

Our views of the higher groups might be expressed thus:

We confess ourselves much disappointed in that part of the work which relates to the Mollusca. Though the general facts and special details of the anatomy are clearly stated, no notice is taken of the plan or arche

typal characteristics of the branch, which were admirably defined by Carpenter in 1854, and by Dana in 1863, and Mr. Morse in 1865,* and nothing is said of the embryology of either the animals or the shells, omissions which are unpardonable in an essay on classification.

The subdivision of the branch into Mollusca and Molluscoida also appears to us objectionable. If Prof. Huxley had drawn his dividing line between the Lamellibranchs and Pteropods we should have had an eminently natural division of the Mollusca, but in placing the line between the Lamellibranchs and the Ascidians he repeats a common error.

The Polyzoa, Brachiopoda, Ascidia and Lamellibranchiata have to the Pteropoda, Gasteropoda and Cephalopoda, within their own type, a negative relation comparable to that which the invertebrata have to the vertebrata; they are, when contrasted with the last three classes, as a whole, without a special cephalized extremity. All the three higher classes have the cephalic region distinctly differentiated from the mantle, or cœnœcial region, whereas in all the lower classes the organs of this region are buried in the mantle, or conocial region, except among the Polyzoa, where they are distinct from the cœncial region, and may be extended in the higher genera, but this differentiation is gained only by elevating the cephalic organs to the posterior pole of the body.

The close structural affinities of the Polyzoa and Brachiopoda are noticed; the two divisions are placed in their correct sequence, and their relations to the Ascidia are defined with equal precision and correctness; but the author fails to see the close affinity of the latter to the Lamellibranchiata. Nevertheless the differences between the structure of the Lamellibranchs and Ascidians are no greater than those existing between the structure of the Polyzoa and the Brachiopoda, whilst the homologies existing between the Ascidia and the Polyzoa are of a much more general character than those existing between the Ascidians and the Lamellibranchs.

The Polyzoa and Brachiopoda together may be considered as one anatomical type, and defined as a sac closed at one end by a disc, surrounded by free tentacles, and perforated by an edentulous mouth from which hangs the alimentary canal.

Among the Ascidia and Lamellibranchiata on the other hand the tentacles, or gills, are always joined by an intermediate membrane, and they together with this membrane form either an open or closed pouch perforated at its lower end by the mouth, from which hangs the alimentary canal.

The atrial chamber has but one aperture in an invaginated Polyzoön or a Brachiopod, whereas with the Ascidia and Lamellibranchiata there are two. The muscular systems of the Brachiopoda and Polyzoa are complicated and homologically similar, as shown by several writers,

*Carpenter's Comparative Physiology, Dana's Manual of Geology, and Mr. Morse's Classification of the Mollusca in the Proceedings of the Essex Institute.

whereas the Ascidia have no distinct muscles which can be compared to those intersecting the visceral cavities of the Polyzoa and Brachiopoda. Mr E. S. Morse has lately shown (September number of the NATURALIST) that the closest resemblance exists between the young of Terebratula and the adult Polyzoön, so close that there would be no hesitation in placing them in the same class, if the characteristics of the former were permanent.

In fact we cannot coincide with those who consider that the principles of the Cuvierian classification are endangered by Mr. Huxley's book. While no champion of all of Cuvier's principles, we cannot but regard any work which wholly sets them aside as very deficient in comprehensiveness; it must necessarily substitute a multitude of details for the very general anatomical statements by which four out of the five great branches of the animal kingdom are usually defined.

THE SHEFFIELD SCIENTIFIC SCHOOL.*-Prof. Verrill reports that the want of funds in the Zoological department has prevented the usual increase of specimens, but that the time has been turned to good account in cataloguing and classifying the general collection, and writing monographs of separate groups. Mr. S. I. Smith has monographed a part of the Decapods, and Prof. Verrill the Polyps and Corals of the west coast of America, and described numerous new forms.

The Geological department, under the direction of Prof. O. C. Marsh, has received several very valuable additions. Among these the most remarkable is a slab with twenty-one footprints of the Otozoum upon it, each of which is about fifteen inches in length. The slab is of a correspondingly gigantic size, measuring twenty by thirty feet.

We have not space to review other departments, but regret to notice that all of them seem to be laboring under pecuniary difficulties.

At Yale we really have a Scientific School, one which gives young men a general knowledge of science and the arts as well as a more intimate acquaintance with some special branch.

The advantages presented by the school in its mode of organization, its corps of instructors and the objects which it seeks to attain for all its students, are of the highest order. We hope, therefore, that the pecuniary hindrances to the future progress of an institution, so important to the general interests of education in this country, may be speedily removed.

NEW ECHINODERMS AND CORALS.†-In this paper Prof. Verrill describes seven new species of Echinoids, five of Asterioids, six of Ophiuroids, and six new species of coral, with one new genus among the Eupsammidæ.

* Fourth Annual Report of the Sheffield Scientific School of Yale College, pamph., 8vo, 76 pp. New Haven, 1869.

On New and Imperfectly Known Echinoderms and Corals. By A. E. Verrill. Ext. Proc. Bost. Soc. Nat. Hist., Vol. xii, pp. 382-'96,

THE RULES OF ZOOLOGICAL NOMENCLATURE.*-In republishing these rules accompanied by many valuable notes and comments, Prof. Verrill has done good service to zoölogy in this country. A copy of these rules and those of the British Association, reviewed by Prof. Gray in a previous number of Silliman's Journal, should be in the hands of every zoölogist.

NATURAL HISTORY MISCELLANY.

MALS.

BOTANY.

ARTIFICIAL PREPARATION OF SUBSTANCES FOUND IN PLANTS AND ANI-Dr. Debus, the President of the Chemical Section of the British Association, states: "It has already become possible to prepare in the laboratory bodies of a very complex character, and which a few years ago were only found in the bodies of animals or plants. Alizarine, the beautiful compound of the madder-root, has been obtained by artificial means in the course of the year by Messrs. Liebermann and Græbe. Results of such a nature render it highly probable that, at no distant period, it will be in our power to prepare, artificially, nearly all, if not all, the substances found in plants and animals. Here I must not be misunderstood. Organic structures, such as muscular fibre or the leaves of a tree, the science of chemistry is incapable of producing, but molecules, like those found in a leaf, or in the stem of a tree, will no doubt one day be manufactured from their elements.-Scientific Opinion.

MAPLE-SEED, THREE WINGED.—I know not if it be common, and, therefore, ask for information, but on a tree of the Acer saccharinum, or sugar maple, in the Central Park in this city (New York) I found, a few days since, a three-winged seed. The description of the genus says, "ovary 2-celled. From the back of each ovary grows a wing, converting the fruit into two 1-seeded, at length separable, closed samaras or keys." (Gray.) I only found this one, though the trees were covered with seed, and I searched pretty carefully for more.-A. M. E.

ZOOLOGY.

KINSHIP OF ASCIDIANS AND VERTEBRATES. The number of Max Schultze's Archiv (v. 4), just published, contains a letter to the editor from Prof. Kupffer of Kiel, in which that distinguished embryologist asserts that he has been studying the early history of a species of Phallusia, and that his results in large measure agree with those of Kowal

* From the American Journal of Science and Arts, November, 1869, at Naturalists' Agency 27 cents.