360 Wortman — Studies of Eocene Mammalia in the 



Microsyops annectens Marsh. 



Bathrodon annectens Marsh, this Journal, voL iv, August, 1872, p. 19, 

 Separata; Microsyops annectens Osborn, Bull, Amer. Mus. Nat. Hist., June, 

 1902, p. 213. 



The type of this species, figure 116, consists of a fragment 

 of a lower jaw of the left side, bearing the last molar. The 

 only character by means of which it can be distinguished from 

 the two preceding species, at least as far as the type is con- 

 cerned, is that of size. This distinction, however, is so pro- 

 nounced that the validity of the species can not be questioned. 

 IIQ The crown of the last molar has 



identically the same structure as 

 that of M. elegans and of M. gra- 

 cilis. The trigon is slightly ele- 

 vated above the heel and the ante- 

 rior cusp is not very distinct. 

 The heel displays its characteristic 

 Figure 116. - Last lower breadth, with the large external lu- 

 molar of Microsyops annectens nate cusp and the Smaller external 



Marsh (type of Bathrodon annec- and posterior CUSps. The posterior 

 teyis Marsh) ; crown view : two • x-j. i. j i. ^.^ ± £ 



and one-half times natural size, ^^^p IS not Situated at the center of 



the posterior border, but very much 

 to the inner side, in a position almost behind the internal — an 

 arrangement which gives an imperfect quadrilateral outline to 

 the heel. This is highly characteristic of the genus Microsyojys, 

 and insures its recognition at sight. 



In the present collection, there are four other specimens 

 represented by lower jaws alone, which give the lower denti- 

 tion in its entirety. The form, proportions, and relations of 

 the other teeth are very like those in the two species already 

 described. 



The measurements of the type are as follows : 



Length of last molar. ,_ 5-8"^°^ 



Depth of the jaw at anterior margin of third molar 11*0 



Measurements of other specimens : 



Length of molar series 16*0"^™ 



Length of second and third molars . _ 10*0 



Length of molars and premolars to base of incisors 30*0 



The type specimen was found near Henry's Fork, by Mr. 

 F. Meade, Jr., of the Yale party, in September, 1871. Addi- 

 tional specimens from the same locality were obtained by Mr. 

 Harger and others. 



