cppE.1 PALEONTOLOGY ^MIOCENE PEEIOD. 475 



in proportion to tlie length tlian others 5 some more clecurved than 

 others. 



With molar teeth as large as those of the Norway rat, the mnzzle is 

 not more than two-thirds as long, so that the species was in general pro- 

 portions smaller and more robust. 



HELISCOMYS, Cope. 



Synopsis New Vert. Colorado, 1873, p. 3. 



Gliar.gen. — ^Inferior molars four; the crowns supporting four isolated 

 cones in pairs. This genus is only known from mandibular rami. These 

 resemble itf their dental structure some of the Muridce, but the number 

 of molars is more, as in Sciuridce. In Myops, Leidy, of the Bridger 

 Eocene, the dental cusps are connected by cross-yokes. 



HELISCOMYS VETUS, CopC, lOG. cit., p. 4. 



Char, specif. — First molar with only three cones ; all the molars except 

 the first with a broad contiguous cingulum on the external side. liamus 

 rather stout ; incisor-teeth very slender, elongate, slightly com2)ressed, 

 with parallel sides and convex anterior face. 



Measurements. 



M. 



Length of molar series 0. 0030 



Length of third molar 0U08 



Elevation of third molar 0005 



Depth of ramus at third molar . 0023 



Length of ramus to end of molars 0010 



The least mammal of the fauna to which it pertains. 



SCIURUS, Linn. 



SciURUS EELiOTUS, Cope. Paramys relictus, Cope, Synopsis New Yert. 



Colorado, 1873, p. 3. 



This species is established on two left mandibular rami, with all the 

 teeth complete. It was referred to the genus Paramys, because I found 

 no dilference between the corresponding parts in the respective species ; 

 but as the characters of the latter are chiefly observable in the maxil- 

 lary teeth, the reference was not final. As it does not differ in any 

 degree from corresponding parts of the existing squirrels, I place it for 

 the present in the same genus with them, as the safer course. 



The teeth increase regularly in size from the front backward. The 

 transverse crests are "marginal, and terminate in cusps at the inner 

 extremity, which are separated by a lower acute median cusp. A 

 longitudinal crest connects the crests just within their outer extremities j 

 it exhibits a loop directed outward. A low ridge passes from the 

 posterior outer buttress, just in front of the posterior margin, in the last 

 two molars. Anterior cusps of first molar contiguous. 



Measurements. 



Length of ramus to end of M. 4 0. 0120 



Length of molars 0083 



Length of third molar 0015 



Width of third molar 0018 



Depth of ramus at third moJar OOHO 



Width of incisor 0015 



Size that of the chickaree, {Sciurus hudsonius.) 



