No. 2391. DESCRIPTIONS OF PLEISTOCENE VERTEBRATA—HAY. 613 



greatest width of the lower end of the bone is 22.5 mm. in M. van- 

 couverensis ; in M. arrodens, 20 mm. 



The ulna of M. arrodens originally had a length of 83 mm. and the 

 humerus is 74 mm. long. In M. vancouverensis the ulna is only 2 or 3 

 mm. longer than the humerus. The bones of M. arrodens are stouter 

 than the corresponding ones of M. vancouverensis. In an ulna of the 

 latter 77 mm. long, the depth in front of the coronoid process is 8 

 mm. ; in 21. arrodens, 9 mm. In a radius of M. vancouverensis the least 

 diameter at the middle of the length is 4 mm. ; in M. arrodens, 5 mm. 

 The ulna and radius of the latter are more bent than in the other 

 species. 



The humerus, ulna, and radius of M. arrodens have been compared 

 with the same bones of M. jiaviventer jiaviventer and M.f. sierrae, from 

 various localities in California, sent by Doctor Grinnell. Both £prms 

 are smaller than M. arrodens and considerably smaller than M. van- 

 couverensis. These two forms of M. jiaviventer differ from M. arrodens 

 in the same way as does M. vancouverensis. 



MARMOTA FLAVIVENTER (Audubon and Bachman). 



Plate 118, figs. 6-8. 



This species appears to be represented in the collection by the rear 

 of a skull preserving the basioccipital, the bullae, the petrosals, and 

 the supraoccipital; also by the remainder of possibly the same skull 

 from just behind the orbits to the front of the maxilla (pi. 118, 

 figs. 6, 7). These have the catalogue number 2655. The nasals are 

 missing; also the incisor teeth and three of the molars of the right 

 side. On comparison with skulls of M. Jiaviventer no differences are 

 noted. The molar teeth are little worn. The interorbital portion 

 of another skull (Cat. No. 2657) is also represented (pi. 118, fig. 8). 

 In this there is a complete postorbital process. Two right rami of 

 lower jaws, or rather parts of them, with some little worn teeth, may 

 belong to these incomplete skulls. 



THOMOMYS FUSCUS (C. H. Merriam). 



Plate 118, figa. 9 and 10. 



This species is represented by a single incisor and by the anterior 

 half of a skull, which contains both incisors, but lacks all the molars 

 and both nasal bones. On comparison with a skull of M.fuscus from 

 that region no differences are observed. The incisors retain much 

 of their original color. 



LEPUS OR SYLVILAGUS, species indeterminable. 



A single right ramus of a rabbit is in the collection. It has about 

 the size of the corresponding part of Sylvilagus nuttallii. 



