2o6 ROCHESTER ACADEMY OF SCIENCE. [April lO, 



cover the expenses of the Popular Lecture Course, the bills to be 

 approved by the President and Secretary. 



The report was adopted, and the appropriation made. 



The following pajier was read by the President : 



THE EVOLUTION OF THE UNGULATE MAMMALS. 

 Bv Herman Lk Rov Fairchild. 

 (Abstract.) 



This group of mammals was divided by Cuvier into two orders, 

 the Ruminants and the Pachyderms. The living Ruminants form a 

 very distinct group, marked by persistent features, namely, horns and 

 hoofs in pairs, upper incisors wanting, stomachs complex, and the 

 habit of rumination. But it was found that the fossil representatives 

 of these orders did not fall into such a classification, and Professor 

 Owen showed that the foot structure was a more persistent and 

 fundamental distinction. The order Ungulata, as now constituted, 

 includes the mammals formerly classed as Ruminants and Solidun- 

 gula, and all those formerly called Pachyderms, except the Probos- 

 cidians. Of the larger mammals, both extinct and living, this is the 

 most numerous and comprehensive order. 



The members of this order walk on the extremity of the toes, 

 which are protected or encased in a greatly expanded nail or hoof 

 (ungula). This apparently superficial character is but one element in 

 the structure of the ungulate foot, which structure is of the utmost 

 value in tracing relationship of the fossil mammals, and the study 

 of it forms one of the most fascinating chapters in Comparative 

 Anatomy. 



The number of digits of full size never exceeds four, at least the 

 first digit being always obliterated. As the limbs are used only for 

 locomotion, never for prehension, clavicles are useless and therefore 

 wanting. The molar teeth are massive, with broad crowns suited for 

 grinding vegetable food, although the primitive species were probably 

 omnivorous, like a few living forms. The brain is proportionately 

 small, and the food canal unusually long. 



The Ungulates were the most numerous and important mammals 

 of Tertiary time, and those ancient species were the ancestors of the 

 present specialized forms, the line of descent being clearly traced in 

 some cases, especially in the horse, the most highly differentiated 

 species. 



