CHEIRONECTES, or CIIIRONECTE..'S (IItiger), a genus of Mar ample' animals. [Mamoru's...1 Cli Cheirepede, it name proposal by Mr. Ogilby for all the maminiferons animals' that are poaseasimi of hands. The following in Mr. Ogilby'a arrangement of his Cheiropeds Mr Ogilby states that observations, commenced in 1829 and continued for more than nix years, have assured him that the non oppoteable character of the inner finger of the anterior extremities, which he first remarked in .31 vete: Senieulus, in not confined to that genus, hut extends throughout the whole of the genera of the South American monkeys, individuals of all of which have, he etaten, been seen by him in a living state. In none of them consequently, ho observes, does a true thumb exist on the anterior limbs; and he considers that it follows as a further connequenco that the whole of them have been hitherto incorrectly referred to the Quadrumana by zoologists generally. The following extract from the 'Proceedings of the V.00logical Society,' for 1836, will explain the views of this naturalist :— "Of the eight natural genera which include all the known monkeys of the western hemisphere, one, Melee, is entirely destituto of a thumb, or has that member existing only in n rudimentary form beneath the skin. In five others, Mycelcs, Layeeltris, Pitheeia, and Hapale, the anterior thumbs (using the ordinary expression for them) are placed absolutely on the same lino with the other fingers, are of the same form with them, act Invariably in the name direction, and are totally incapable of being opposed to them. in the two remaining genera, Cebu: and Callithrix, the extremities of the anterior limbs have a greater external resemblance to the hands of man and of the monkeys of the 01(1 World : the internal finger in placed farther back than the general line of the other fingers, and has on that account, when superficially noticed, the semblance of being opposed to them ; but, as has been correctly observed by D'Azara with reference to C. capacious, it Is lean separated than In man : it is besides of precisely the same slender form with the rest, is weaker than them, absolutely without power of'oppoaition to them, and habitually acts 111 the same direction with them. The impression derived from contemplating the hands of the Old World monkrya might induce the belief that the extremities of the au are similarly constituted ; but if the knowledge that in Piaccia, there are no opposoable thumbs 10a0.1 ton close observation of the anterior extremities of the Ceti, it will be found that they do not act as hands and osnnot be considered as paste sing the powers of those organs. From Innumerable observations of many species of that genus, Mr. Ogilby atates.thot it was very evident, notwithstanding the fallacious appearance occasioned by the backward position of the organ, that they had not the power of opposing the thumbs to the other fingers in the act of prehension ; and in fact their principal power of prehension seems to be altogether independent of the thumb, for generally speaking that member was not brought into action at all, at least not simultaneously with the other fingers, but hung loosely on one aide, an Mr. Ogilby has seen it do In like drown
stances in the Opoasums, Pludnngern, and other arboreal mammals: when actually brought into play however the thumb of the Cebi Invariably acted in the name direction as the other fingers. Want consequently agrees 111 the character of non-oppossableneas of thumb with the nearly allied goners. And in this hitherto unsuspected peculiarity zoologists obtain a fnr,morn important character by which to distinguish the monkey? of the Old and Now World than that hitherto relied on, the comparative thickness of the septum narium, or than the accessory aids afforded by the absence of cheek-pouches and callosities. Hence, according to Mr. Ogilby, as the monkeys of America have now been ascertained to be destitute of anterior hands, they can no longer be inoluded among the Qoadrumono, and ho proposes in consequence to regard them an Petfirnana. Ile conaiders that the latter series, the monkeys of America, form a group parallel to that of the monkeys of the Old World among the Qundrumana and viewing the Quadrumana an consisting of two primary groups, that of which Simla forms the type, and the Lemuruhr, ho proceeds to analyze the Pedimana, in order to determine whether auy group analogous to the Lemurs exists In it. Ile finds such n group in the association of the genera IhVe11,1Ws, Cheirenceles, Phslanyista, Petatsrus, and Phascalarctoe (together with a new genus, Pseadochirus, which he has found it necessary to separate from Phalanyista an at present constituted); and for thin association he uses the name of Didelphithr. Aware that the modifications observable in the dentary systems of these several genera have been regarded by many zoologists as betokening a difference of regimen, which has led to their being viewed as constituting distinct finuilies, he in the first place states, as the of his observation of the habits of the numerous species of all these genera which have been from time to time exhibited In the Society's Gardens, that there is little or no difference in this respect between the Opossums and Phalniigers, but that all are equally omnivorous ; and then proceeds to discuss the modifications that exist among them in the number and forma of the several kinds of teeth, which ere not in his eatiinntion no very different in reality between the Opossums and Phnlangers as they appear to be at first night. In further support of his opinion that this association of genera forms a natural family, Mr Ogilby refers to the gradual and uninterrupted transition from the naked-prehensile tailed Opossums of South America, through the equally naked-tailed Couscous, Balantia, of the Indian bales, to the tans Plinlangens ; and from these to the Petaurints directly on the one hand, and by means of the Pscudocheirs to the Koalas on the'other.