INSTITUTE OF SCIENCE, PHILADELPHIA. 



39 



The second figure represents a third large upper 

 molar, in which the triturating surface presents 

 rather more folding of the enamel than is com- 

 monly observed in the corresponding tooth of the 

 Domestic Horse. The measurements of the tooth 

 are as follows : 



Length of crown at the fore part outward, 70 mm. 

 Fore and aft breadth of triturating surface, 31.5 " 

 Transverse " " " 31 " 



An inferior molar measures 33 mm. fore and aft and 22 mm. trans- 

 versely. 



A lateral incisor has no pit, but is slightly incurved at the sides. It is 

 20 mm. in breadth. An intermediate incisor on the worn triturating sur- 

 face is 22 mm. broad transversely and 13 mm. fore and aft. 



Incidentally maybe described a specimen, the fragment of an upper jaw 

 with teeth of a Horse, submitted to my examination by Prof A. H. Worthen, 

 State Geologist, Springfield, Illinois. It was found in a bog on the confines 

 of Bond and Fayette County, Illinois. A view of the triturating surfaces 

 of the teeth is represented in the subjoined woodcut. 



The teeth in the jaw consist of the anterior small premolar and the 

 succeeding three large ones, all worn sufficiently to display the course of 

 the enamel on the triturating surfaces. From the size of the teeth and the 

 greater degree of folding of the enamel than is seen in ordinary varieties of 

 our Domestic Horse, I suspect the specimen to belong to the indigenous 

 species Eqiius major ; though it may be a fragment from a variety of the 

 introduced Horse. In the specimen, in the maxilla, which is preserved in 

 advance of the premolars to the premaxillary articulation, in a distance of 

 3j^ inches, there is no trace of a canine alveolus. The measurements of 

 the fossil are as follows : 



