832 THE JOHN DAY FAUNA. 



Meniscomys nitens Marsh. 



Allomya nitena Marsh, Amer. Journ. 6ci. Arts, 1877, September, p. 253. Mesniscomyt multiplioatm Cope. 

 Proceedings Amer. Philosoph. Society, 1878, p. 68. 



Plate LXIII; figs. 16-17. 



Represented in my collections by fragmentary jaws of eight individ- 

 uals, two of which contain superior molar teeth. These indicate a species 

 which has some range of size, and which may be nearly as large as the M. 

 lioloplius. 



The characteristic peculiarity of this species is, that there are two much 

 crenate intermediate tubercles on the posterior side of the superior molar 

 tooth, which are connected by a ridge with the posterior V ; and that the 

 anterior intermediate tubercle is part of a crenate ridge which connects the 

 inner crescent with the anterior V. The external face of the crown is 

 prominent at the notches between tlie Vs. 



The inferior molars are bilobate on the external side, and while the 

 inner sides of the crowns are flat, their superior edge is trilobate. The 

 grinding-face is much complicated by enamel ridges. Four crescentic areas 

 are discernible on the worn surfaces of the crown, of which the posterior 

 is reduced in size on the middle two molars. The two inclosed lakes have 

 very plicate borders which form many small loops, and sometimes they are 

 fnsed into a single irregular area. The last molar is extended a little poste- 

 riorly, and all present an entrant angle between the inner columns. The 

 coronoid process originates opposite the third molar, and the masseteric 

 ridge ceases below the middle of the jaw below the second molar. 



Measurements. 



M. 



Length of Pm. iv and M. i 0060 



_,. , !• n • < anteroposterior 0040 



Diameters of Pm. w I *^ ,,., „ 



< transverse UU4U 



_^. , -„ T i anteroposterior 0020 



Diameters of Pm. I. •; , ^ ..,_ 



( transverse 0U4U 



Probable length of inferior molar series 0120 



Length of posterior three molars 009.5 



.^. ^ . , , (anteroposterior 0030 



Diameter of second molar { , '^ .^. 



c transverse OOa."! 



Length of fourth molar 0040 



Depth of ramus below second molar 0070 



Width of ramus below second molar 0050 



