236 PROCEEDINGS OF THE ACADEMY OF [1894. 



Crania] measarementx of tijpe. — Total length, 54 ram ; basal 

 length, 4().5; basilar length of Hensel, 44; zygomatic breadth, 27; 

 upper molar series on crowns, 10. 



Hodomys vetulus sp. nov. (Text fig. 3, c and d.) 



Type from Tehuacan, Puebla, Mexico. No. 53,f)56 $ ad., U. S. 

 Nat. Museum, Department of Agriculture Collection. Collected 

 May 8, 1893, by E. W. Nelson. (Original number 4,784.) 



General cliaracter><. — This animal bears no close resemblance to 

 any known species except Hodomys alleni from Mazanillo (on the op- 

 posite side of Mexico), with which it shares the remarkable S-shaped 

 last lower molar, peculiar audital bulla;, closed sphenopalatine vacui- 

 ties, and many other characters. It is much smaller than alleni, has 

 a bicolor instead of concolor tail, white instead of dusky hind feet, 

 and diifers also in cranial characters. 



Color. — Upper parts dull fulvous from point between eyes to rump, 

 plentifully mixed with black hairs; face gray; fore and hind i'eet 

 white ; tail bicolor, blackish above, soiled white beneath ; under 

 parts whitish, clouded from plumbeous under fur and washed with 

 dull fulvous on sides of belly (and in one specimen on breast also). 



Cranial characters. — Skull similar to that of Hodomys (dleni, but 

 smaller, shorter, less angular, and differing further in the following 

 characters: rostrum and nasals shorter ; nasals narrower posteriorly; 

 interparietal shield lass quadrate and more elongated transversely ; 

 incisive foramina shorter (falling considerably short of plane of m ' ) ; 

 palate proportionally longer ; audital bulhe smaller; frontals broader 

 posteriorly and less upturned along orbital margins ; mandible less 

 expanded posterioidy. 



Dental characters. — Similar to H. alleni, but m i broader and 

 shorter; the antero- external loop larger; postero- internal loop less 

 completely divided ; m -j broader and shorter ; more perfectly 

 S-shaped, and without trace of antero-external sulcus. 



il/m.syn-ewuwys (taken in flesh). — Type: Total length, 3-^0 mm ; tail 

 vertebra}, 106; hind foot, 38. Ear from anterior base, 29 (in dry 

 skin). Average measurements of 4 specimens from type locality : 

 Total length, 365; tail vertebne, 163; hind foot, 38. 



Cranial measurements of type. — Total length, 47; basal length, 41; 

 basilar length of Hensel, 39; zygomatic breadth, 25 ; upper molar 

 series on crowns, 9. 



