TO THE LOWER ANIMALS. 97 



Similarly the occipital foramen of Hycetea (Fig. 17) 

 and still more of the Lemurs, is situated completely in the 

 posterior face of the skull, or as much further back than 

 that of the Gorilla, as that of the Gorilla is further back 

 than that of Man ; while, as if to render patent the futility 

 of the attempt to base any broad classificatory distinction 

 on such a character, the same group of Platyrhine, or 

 American monkeys, to which the Mycetes belongs, con- 

 tains the Chrysothrix, whose occipital foramen is situated 

 far more forward than in any other ape, and nearly ap- 

 proaches the position it holds in Man. 



Again, the Orang's skull is as devoid of excessively 

 developed supraciliary prominences as a Man's, though 

 some varieties exhibit great crests elsewhere (see p. 54) ; 

 and in some of the Cebine apes and in the Chrysothrix, 

 the cranium is as smooth and rounded as that of Man 

 himself. 



"What is true of these leading characteristics of the 

 skull, holds good, as may be imagined, of all minor fea- 

 tures ; so that for every constant difference between the 

 Gorilla's skull and the Man's, a similar constant difference 

 of the same order (that is to say, consisting in excess or 

 defect of the same quality) may be found between the Go- 

 rilla's skull and that of some other ape. So that, for the 

 skull, no less than for the skeleton in general, the proposi- 

 tion holds good, that the differences between Man and the 

 Gorilla are of smaller value than those between the Gorilla 

 and some other Apes. 



In connection with the skull, I may speak of the teeth 

 organs which have a peculiar classificatory value, and 

 whose resemblances and differences of number, form, and 

 succession, taken as a whole, are usually regarded as more 

 trustworthy indicators of affinity than any others. 



