Zoological Society. 487 



manner, and that the supraorbital foramen and groove are entirely- 

 wanting. This induced me to examine with care the unique speci- 

 men in the Museum of the College of Surgeons, and I thus con- 

 firmed these characters, and also found that the mark indicating the 

 origin of the obliquus inferior oculi is but a slight depression, not 

 more marked than I have seen it in some skulls of Rhinoceros and 

 Hyrax, and not placed in a fossa, but simply upon the general uni- 

 form concavity. Although the posterior portion of the skull is en- 

 tirely lost, yet enough remains to show that there was but a slight 

 difference of level between the base of the cranium and the palate ; 

 and to the inner side of the posterior molars there is just sufficient of 

 the matrix removed to show a slightly raised curved line whose place 

 is about that which the edge of the posterior nasal opening should 

 occupy, if the animal be organized upon the true Perissodactyle 

 type. A further confirmation is afforded by the distinct appear- 

 ance of a groove, whose broken edges testify the loss of the little 

 piece with which the alisphenoid canal should be enclosed ; so in 

 the only fragment we possess every character that remains agrees, 

 to help us through the difficulty in which the ambiguous dentition 

 leaves us. 



May I be permitted to express the hope, that before forming a de- 

 cided judgement on these matters, naturalists will carefully investigate 

 for themselves ; recollecting, that so long as man is not infallible, the 

 continued progress of research must with new discoveries find some- 

 thing to be corrected in that which has been done before ? but what- 

 ever be the judgement on these points of difference, I trust that doubts 

 will cease as to the truth of the original idea, which nought but error 

 hindered from being sooner developed ; and that one important step 

 may thus be gained towards that correct appreciation of the compa- 

 rative value of groups, which we must attain throughout organic na- 

 ture, before further generalizations can safely be attempted. 



I will conclude by giving a hst of genera arranged as I should now 

 propose ; the characters of the groups, although many remain to be 

 discovered, are already too numerous to be again repeated, and I only 

 include such genera of which I have been able to examine skulls ; or 

 in the case of fossils, of which actual specimens, casts, or well-authen- 

 ticated figures of some characteristic portion of the skeleton have come 

 within my observation. 



ARTIODACTYLA. 



RUMINANTIA. NON-RUMINANTIA. 



Merycopotamus. Ilippopotamidce. 



Chalicotherium*. Hippopotamina. 



Bovidce. Hippopotamus. 



Sivatherium. Hyopotamus. 



Anthracotherium. 



Bos. Choeropotamus. 



* Of these two genera I have not yet sufficient evidence to determhie the 

 family. 



