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in the skull of Cebus to the human skull, a resemblance which is still more striking in the Marmozets.

In the enunciation of Geoffroy's law as above given by himself, there are two elements, which must be examined separately. We will first take that one which I conceive to be the less important of the two, because it is not involved in the terms I have before mentioned; which may be thus stated that the apertures of the nostrils of monkeys belonging to the old world are below the nose, ("au dessous du "nez,"-St. Hil.; "inférieures,"-Latreille); while those of the monkeys of the new world are lateral (" ouvertes sur les "côtés du nez." St. Hil.) Now I think that if, on a fair profile view of any monkey, the whole opening of the nostril can be seen in its full circumference, without foreshortening, that opening cannot be said to be otherwise than lateral; for if it might be otherwise considered, that character would become valueless as a differential sign. It being granted then, that such a nostril has a right to be considered lateral, let us next see whether this lateral nostril is confined to the monkeys of the new world, and whether indeed it be constant among them.

I do not hesitate to say that the description of a lateral nostril above given applies, not to the new world Quadrumana alone, but also to many of those of the old world. I might instance several of the Semmopitheci, in which the whole nostril is seen on a side view, especially S. Siamensis. Of the genus Colobus are some well-marked examples, especially the Guereza (C. Guereza), in which we may absolutely distinguish a larger aperture in the nostrils on a side view than on any other aspect (fig. 6); and in some of the Cercopitheci the character is only less marked. The Magot (Macacus Inuus) discloses the full size of his nostrils on a profile view; and I think, the terminal nostrils of the Cynocephalous baboons might be considered as negative evidence against the applicability of the "narines

66 'inférieures," of Latreille and St. Hilaire to the Old world monkeys. Indeed, when taken strictly, the only monkey which I can understand as having nostrils opening "au dessous du nez,” is the Proboscis monkey (Nasalis larvatus); and some, as the Chimpanzee, for example, I should be more inclined to call "au dessus," or "supérieures," for they open upwards rather than in any other direction.

But not only do some of the Old world monkeys possess lateral nostrils, but certain New world monkeys have them opening to the front. I admit that in those Platyrrhini in which the nostrils do open to the side (as Cebus hypoleucos) and which constitute the majority, the lateral opening is more decided than in any old-world monkey whatever, but there are exceptions. These are certain species of the genus Ateles, for instance, A. Beelzebuth, and all the genus Eriodes (fig. 4). In none of these can anything like a full view of the opening of the nostrils be obtained on a profile aspect. Indeed, of the genus Eriodes, containing three species, a late work on the Quadrumana says: "They have the nostrils opening in"feriorly," thus allowing at least one exceptional genus.

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We will now examine the other, and more important element of distinction; and the one which has given rise to the names Catarrhini and Platyrrhini; viz., the size of the nasal septum, which is said to be narrow in the old world, and wide in the new world monkeys.

The nasal septum of some of the genus Colobus is as wide as many, and wider than some of the Platyrrhine group, and this is especially apparent in the Guereza (C. Guereza) (fig. 5) which I have before mentioned as having the nostrils opening laterally. The septum here measures half an inch in width; and it is scarcely less apparent in the Colobus ursinus. In many of the Cercopitheci, it is far above the average width, as for

Ils ont les narines ouvertes inférieurement-Chenu, Hist. des
Quadrumanes, p. 197.

example, in C. cynosurus and C. samango. Among the new world monkeys, where we are taught to look for very wide septa, I may again instance the genera Ateles and Eriodes (fig. 3) as exceptional; and, indeed, I believe that in the first and most typical group of American monkeys (the Sapajous) the nostrils are, as a rule, situated more close together than in the second and third, or more aberrant, groups, the insectivorous Geopithecs, and the rodent Marmozets. In Ateles Beelzebuth, it is not so wide as in many Catarrhini, and the genus Eriodes (Brachyteles) is confessedly exceptional in this, as well as in other particulars. Thus in the work last quoted, we read "Eriodes. Nostrils rounded, very close together (très rappro"chées), and rather inferior than lateral; nasal septum very slightly thickened;"* and in explanation of this misfortune we read further †—" The genus Eriodes is very remarkable, and seems to establish the transition from the monkeys of the old "to those of the new world; they have the nostrils opening 'inferiorly, but all the other characters class them among "American monkeys;" and indeed this septum of Brachyteles hypoxanthus is only one-eighth of an inch in thickness. Of the genus Nyctipithecus also it is said ‡— Nostrils separated by a very narrow septum, and opened sometimes on the side, and at the same time below the nose.

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Here, then, we have a genus which in every other respect resembles the Platyrrhini, but in this important one, on which the distinctive name is founded, they are exceptional.

So much for instances; and having such before us, it cannot be matter of surprise that Sir Wm. Jardine,§ when speaking of the new world monkeys, in a popular work, has

* Narines arrondies, très rapprochées l'une de l'autre, et plutôt inférieures que latérales, cloison nasale très peu épaissie.-Chenu, p. 197.

+ Les Eriodes sont très remarquables, et semblent établir le passage des singes de l'ancien continent a ceux du nouveau monde; ils ont les narines ouvertes inférieurement, mais tous les autres caractères les classent parmi les singes Américains.-Op. cit. p. 197.

Op. cit. p. 224.

Naturalist's Library vol. i, Mammalia, p. 162.

omitted to include the nasal characters among the most striking outward differences."

And here let me not be thought presumptuous or captious in finding fault with what has now so long been current and unquestioned. I do not by these observations intend to infer that a character franked with the name of St. Hilaire, and subscribed to by so many eminent naturalists, is, after what I have said, valueless. On the contrary, I believe that the terms Catarrhini and Platyrrhini are of great significance to one well acquainted with the Quadrumanous types, and who does not require to make these distinctions a steppingstone to such an acquaintance. I even grant that the Guereza, a Catarrhine monkey, which, nevertheless, has lateral nostrils and a wide septum-both characters belonging to the other group is nevertheless very distinct from that other group, even in those very characters which it has in common with it; and this paradoxical remark can only be fully understood by one who is acquainted with the typical characters of the two groups; although I hope before I conclude to render it less obscure.

It appears to me that correctness of description demands. that the far too general expositions of the terms applied to the two great families of monkeys by the eminent French naturalist should be revised and qualified to meet the numerous exceptions to which I have referred.

Having, then, pointed out the defects of the definitions of the terms Catarrhini and Platyrrhini, and shown that, important as those terms are, the characters ranked under them are not constant, it may be asked: If there is so much significance in these terms, is it not possible to discover some character which is constant and peculiar to both-some invariable mark by which the mere tyro could at once pronounce the native soil of any one of these animals, whether in the new or the old world? My answer is that, believing from the very nature of things

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