358 QUADRUMANA. 



In the Journal de Physique, Messrs. Cuvier aud Geoffrey announced 

 their discovery of a method whence, as they conceived, correct and 

 philosophical data could be obtained, upon which to institute an arrange- 

 ment of the animals under discussion : this was by measuring the degree 

 of the facial angle (a process originally invented by Camper), and of 

 making the degree, thus ascertained, the test both of rank in the family 

 and of natural affinities. But a plan of this kind cannot be adopted 

 with precision ; and is, at best, calculated only to mislead. In their 

 progress from youth to maturity, the skulls of the Simiadae universally 

 undergo very marked changes ; and, besides, there is much difference be- 

 tween the crania of males and females. It happens, also, that the most 

 anthropoid species, the Chimpanzee, has, when adult, the muzzle more 

 produced, and, consequently, the facial angle more acute, than the 

 Gibbons or the Semnopitheci ; in fact, as much so as the Baboons ; 

 so that the facial angle, even where correctly ascertained, will be found 

 to be nearly the same in species widely differing from each other in 

 structure and general economy. The fallacy of this rule being felt, 

 naturalists, without abandoning it (and the same observation applies to 

 the tail), have sought for other characters, by which, in conjunction with 

 this facial angle, the natural groups of this family might be distinguished. 

 Of these, the shape of the teeth ; the presence or absence of laryngal 

 sacculi, and of cheek-pouches ; the presence and magnitude of callosi- 

 ties ; the condition of the thumb ; and the length of the tail, are the 

 principal ones upon which naturalists have founded the modern sub- 

 divisions. There is, however, a want of fixedness in these characters ; 

 they do not accompany each other in the same unvarying order, but are 

 often perplexingly interchanged ; so that it becomes impossible to gene- 

 ralize on them. If, for instance, it be laid down as a rule, that all the 

 Monkeys with callosities and tails possess laryngal sacculi, and a fifth 

 tubercle on the last molar below, we shall find it, though of extensive, 

 not of universal application ; for the Cercopitheci, with two exceptions, 

 have the last molar destitute of the fifth tubercle ; and many, certainly, 

 want laryngal sacculi. 



Again, the Gibbons, allied as they are to the Orang, possess small 

 callosities ; and the Chimpanzee, placed by Cuvier in the same genus 

 with the Orang, is destitute of those external laryngal sacculi which, in 

 this latter animal, and in the syndactyle Gibbon, are remarkable for 

 development. The fact is, that the very variableness of these charac- 

 ters proves their non-importance beyond a certain point, no less than 

 the impossibility of taking them, unitedly or singly, as the standard of the 

 natural groups composing the family. With these difficulties around 

 him, the naturalist will find them vanish, if he proceed at once to analyze 

 the family, and to determine, according to the results of his analysis, the 



