rodential animals. The Cheíromys, consequently, is not in reality so abnormal in the present family as in those with which it has been hitherto associated; the form of the head and extremities is in all respects the same, and even the organs of mastication are not very dissimilar. Here, then, is the natural situation of this singular being in the scale of animal life, and here, associated with its natural congeners, its apparent anomalies vanish, and it takes its place as a regular constituent part of a natural and well-defined group. It is only, indeed, the absence of the marsupial character which would make us hesitate to unite the Cheíromys with the Didelphidæ ; but this circumstance is so material as to require that it should be placed in a different subfamily. At the same time, its analogy to the Rodéntia ought not to be overlooked; and it is for the purpose of expressing this relation that I propose to denominate the small group which I am obliged to form for this animal, Glíridæ. I suspect, indeed, that the Cheíromys bears a more intimate relation to the real dormice (Glís) than we are yet aware of.*

Hitherto, I have intentionally abstained from alluding to the bimanous type of organisation as exemplified in man. It is now necessary to consider that form, and investigate the relations which subsist between the Bímana, Quadrùmana, and Pedímana, between all those mammals, in short, which are provided with opposable thumbs, either upon one or both pairs of the extremities. Baron Cuvier, as it is well known, places man in an order by himself, apart from the Símiæ and Lemurida; but Baron Cuvier knew nothing of the relations here developed, and shown to subsist between the Quadrùmana and Pedímana, properly so called; and, in other respects, the separation in question depends rather upon moral and intellectual, than upon physical and zoological, data. The naturalist, however, must view man in a different light from the metaphysician and the divine; anatomical structure and organic conformation are the only principles which the zoologist can admit as the foundations of natural science; and, in this respect, man is too closely connected with the apes, and other Símiæ, to admit of being placed so widely apart from them as he has been in all recent classifications of mammals. I do not mean to affirm that the bimanous form approximates

* I have not yet seen the Cheíromys, but am inclined to think that it may, after all, belong to the Lemùridæ, with which it is associated by Desmarest, and with which it agrees in structure and habitat; the loss of prehensile power in the fore thumb being but a similar phenomenon to the entire absence of that organ in the Semnopithècus and A'teles.

so nearly to the quadrumanous as this does to the pedimanous, but that the whole three form so many constituent and subordinate groups of the same natural order, and are united by a chain of affinities too strong to be arbitrarily dissevered. At the same time, the Bímana have peculiar and appropriate characters, which, even in a physical point of view, exalt them sensibly above the allied families. The very separation of the functions of locomotion and prehension, and their appropriation to different organs, gives man a notable superiority over all other mammals; for by this means the organs of touch and prehension preserve their delicate and sensitive structure unimpaired by contact with the hard and rough ground. They are, besides, resident in that pair of the extremities which is situated in the immediate vicinity of the organs of sense and mind, and thus in the most convenient situation possible for executing all the various commands of the will; whilst the erect station of the body, and the appropriation of the function of locomotion to the posterior extremities alone, prevents them from being interfered with in the execution of these essential duties. The Quadrùmana, on the contrary, continually obliged to employ the anterior as well as the posterior extremities in the act of progression, have the sense of touch and power of prehension seriously diminished in consequence; whilst the Pedímana, with the proper organs of prehension upon the posterior extremities only, are placed in still more unfavourable circumstances with regard to the facility of executing these functions, or obeying the commands of volition. In fact, the hind thumb in pedimanous and quadrumanous mammals is manifestly designed for no other purpose than to assist the function of locomotion, by giving those animals a more perfect power of prehension in grasping the branches of the trees among which they habitually reside; but the Quadrùmana have the farther advantage of anterior hands, which the Pedímana do not possess, which adapt them to still more important acts of prehension, and approximate them more closely to the human type. They consequently occupy an intermediate position between the Bimana and Pedímana, with which they are connected by means of the real Apes (Pithecus) on the one hand, and of the Simìadæ of South America on the other. The entire group thus presents a beautiful gradation of zoological characters from man to the Símiæ, and from those to the Sapajous, Sagoins, and Opossums, and an uninterrupted chain of the most important affinities, which clearly vindicate its right to be considered as a strictly natural family of mammals; whilst the important

and influential character of opposable thumbs, either upon one pair of the extremities or upon both, definitely distinguishes it from all other groups, and renders it at once easy to recognise, and susceptible of a strict logical definition. This principal group or order of mammals, which I propose to call Cheiropeds (Cheirópoda), in allusion to the circumstance which forms their most important character, with its subordinate groups, or families, of Bínana, Quadrùmana, and Pedímana, and the still more subordinate subfamilies which compose the latter two groups, is accurately defined and represented in the following table : —

ART. IV. Illustrated Zoological Notices. By EDWARD CHARLESWORTH, F.G.S., &c.

1. On the Power which the Animal of the Argonaut has of repairing Breaches in its Shell.

2. On the recent Discovery of a Fossil Crocodile at Whitby.

3. On a Form of chambered cephalopodous Shells, connecting the Genera Nautilus and Ammonites.

THE difference of opinion entertained respecting the legitimate tenant of the shell called the Argonaut, or Paper Nautilus, has given rise to more interesting discussion, and furnished materials for a greater display of ingenious reasoning, than perhaps any other question that has agitated the philosophical world in connexion with zoology. A doubt may, perhaps, even be hazarded whether the true interests of science would be advanced by a termination of the controversy, either from demonstrating the Ocýthöe to be the constructor of its shell, or by discovering the mysterious creature, if such really exist, that frames a habitation for another being, and of whose nature we are as profoundly ignorant as of the animals which inhabited the extinct testaceous genera occurring in the rocks of the Silurean system, or mountain limestone series. The researches undertaken for the purpose of arriving at a solution of this obscure problem, whether by direct experiment upon the immediate subject of dispute, or by attempting to discover in allied organisms conditions which shall reconcile the apparently anomalous points in the history of the genus Argonaúta, cannot fail to evolve facts more or less interesting when considered in relation to comparative anatomy and physiology, although the ultimate object of the investigation may never be attained. I had long, in common, probably, with many others, wondered that no series of experiments, similar to those lately instituted by Mrs. Power, and still more recently repeated by Captain Rang *, had not been attempted by some of the naturalists whose opinions and personal observations are on record in reference to the relation existing between the Ocýthöe and its shell; since the power of repairing its dwelling in common with other conchyliferous Molluscs, naturally suggests itself as a simple and satisfactory refutation of the parasitic propensities attributed by many to this Cephalopod. Upon reading Captain Rang's description of the important distinction which he remarked between the original shell and the diaphragm with which the Ocýthöe repaired the breaches artificially made in its habitation, it immediately occurred to me that, if both his

See Mag. Nat. Hist. for Sept. 1837, p. 393.

experience and that of Mrs. Power coincided in this particular, I had only to discover, if possible, specimens of the Argonaut exhibiting removed portions replaced with true shell, and the experiments of both these parties would go very far towards proving the very reverse of the position which it was the object of Mrs. Power to establish.

With this end in view, I determined to inspect all the collections of shells, whether public or private, within reach, considering it at the same time not a little remarkable that I could not call to mind ever having seen a repaired Argonaut, although this shell, from its extreme delicacy and large size, might be reasonably supposed more liable to fracture than, perhaps, any other. It was in the collection of Mr. George B. Sowerby that I was first fortunate enough to meet with the object of my search. The figure (fig. 64.) represents a specimen which he had had reserved, from the circumstance of its having been broken and subsequently repaired; and he informed me that this was the only instance of the kind which had come under his observation during his whole experience as a scientific conchologist and dealer in shells. One specimen, however, was to me as good as a thousand to establish the fact which I was desirous of proving, that of the constructor of