2l6 Bulletin American Museum of Natural History. [Vol XIX, 



Gymnoptychus minimus, spec. nov. 



A smaller species than G. miniitus Cope. Fourth lower 



premolar larger in proportion 



to the rest of the dentition, 



y/y;/ its anterior and posterior 



.^ I 1 I 1 ,^^ halves of equal width; while" 



1 I ^ ' in G. miniitns the anterior 



half of P4 is much narrower 



than the rest of the tooth. 



The first and second molars 



Fig. II. Gyiunopiychus minimus. Type n o t-rr-,TS7/3-r -t-Vican in H miu- 



specimen. four times natural size. A, in- are UarrOWCr tnaU Ul Lr . 111111- 



ternal,^', crown view. ^^^^^^^ ^^^ ^j^^ wholc molar 



series is thus much more uniform in width. 



Only one specimen of this tiny rodent was found by our 



party. 



Aleasurements. 



Length of dentition, tip of incisor to m^ 8.4 mm. 



" " molar-premolar series, P4— nij 3.5 



" true molars, mi_m3 2.6 



LEPORID.'E. 



Palaeolagus temuQodon Douglas. 



This species is nearly related to P. haydeni of the Oreodon 

 Beds. We have for comparison a series of about seventy- 

 five jaws, upper or lower, but nothing more complete. Mr. 

 Douglas distinguished the species by the presence of an an- 

 tero-external groove on p^.^ On comparison of our series 

 with several hundreds of jaws of P. haydeni in the Amer- 

 ican Museum collections, we are able to add a number of 

 other changes less obvious on a single individual, owing to 

 the great variation that age brings about in the characters of 

 the teeth. 



The size appears to be nearly constant, approximating that 

 of the smaller specimen described by Mr. Douglas, which, as 

 the first measured specimen, is the type of the species. The 

 molars, and especially the premolars, are less hypsodont than 



^ Mr. Douglas says p^, but this must be a slip of the pen. 



