Marsh Collection^ Peahody Museum. 361 



Microsyops Schlosseri sp. nov. 



This species is founded upon a fragment of a left mandibu- 

 lar ramus, figure 117, bearing the second and tliird molars, 

 together with two fragments of the upper jaw containing the 

 first and second molars in one, and the second molar in the 

 other. There is also an anterior portion of a jaw, bearing a 

 part of the incisor and the premolars much worn, which I like- 

 wise refer to this form. 



The chief difference between this ^^„ 



species and M. annectens is one of 

 size. It exceeds M. annectens to %^ 



about the extent that the latter 



exceeds M. gracilis. Another fea- ; \^ ^&^ 



ture of importance is seen in the 

 wrinkled surface of the enamel, /l"^^*^ ifi 

 especially in the valley of the heel, 

 where it is quite rugose. The 

 anterior cusp of the trigon is small, Figure 117.— Upper and lower 



though distinct, in the crown of ^,«^^f ^^ Microsyops Schlosseri 

 ., J?' . T i' , • j_- n T,,i Wortman; side and crown 



the first molar ,_ but consists Ol little views ; one and one-half times 

 more than a thickened cingiilum in natural size. (Type.) 

 the second. The internal cusp of 



the trigon is broken, but apparently had about the same degree 

 of elevation as is usual in the other species. The jaw is notably 

 heavier than that of 3f. ctnnectens. 



Associated with the type lower jaw is a second upper molar 

 which seems to be too much worn to belong to the same indi- 

 vidual. The specimen, however, was collected by Professor 

 Marsh himself, and knowing his great care in such matters, 

 there must have been in the manner of their occurrence very 

 good reason for putting the two together. A second isolated 

 fragment of an upper jaw includes the first and second molars. 

 The chief characters of these teeth are as follows : The outer 

 cusps are moderately flattened externally; the mesostyle is 

 distinct, though small ; the intermediates are as in the other 

 species ; the postero-internal cusp is represented by little more 

 than a cingulum in the second, but is more distinct in the first ; 

 the enamel is rugose. 



The following are the chief measurements of the type and 

 of the upper molars referred to this species : 



Length of second and third lower molars _ 12-0'"™ 



Length of last lower molar 1. 6 "5 



Depth of jaw at anterior border of third molar lO'o 



Antero-posterior diameter of first and second upper 



molars . 10-5 



Transverse diameter of second upper molar . _ 6-0 



