Osgood Thirty New Mice of the Genus Peromyscus. 63 



species. In this respect it approaches a similar condition frequently 

 found in specimens of the melanophrys type. It is easily distinguished 

 from melanophrys by the absence of any definite supraorbital ridge and 

 by its larger audital bullse. Its relationship to difficilis is by no means 

 remote, but its skull differs in the same respects as that of felipensis. 



Specimens examined. Total number, 65, from localities in Mexico as 

 follows : Oaxaca, Coixtlahuaca, 16, Marques, 5, Tamazulapam, 13 ; Puebla, 

 Chalchicomula, 9 ; Tlaxcala, Apixaco, 2 ; Vera Cruz, Maltrata, 5, Perote, 1 5. 



Peromyscus bullatus sp. nov. 



Type from Perote, Vera Cruz, Mexico. Adult female, No. 54,405, U. S. 

 National Museum, Biological Survey Collection, June 3, 1893, E. W. 

 Nelson and E. A. Goldman. 



Characters. Related to P. truei and P. difficilis ; audital bullse greatly 

 inflated, larger than in any other known species of the genus; external 

 ears very large ; tail shorter than head and body. 



Color. Very similar to that of P. truei, but richer, more tawny ; sides 

 and ground color of upper parts tawny ochraceous; middle of back with 

 considerable dusky producing a broccoli brown effect ; top of head and 

 nose broccoli brown ; sides of head between base of ear and eye distinctly 

 grayish; a narrow dusky orbital ring; under parts pure creamy white; 

 feet white with a dusky patch on ankle; tail bicolor. 



Skull. Similar in general to that of P. truei ; smaller than in P. difficilis ; 

 audital bullse very much inflated, actually as well as relatively larger than 

 in any other known species of the genus ; braincase rounded and some 

 what inflated, much as in truei ; interorbital constriction relatively wider 

 than in difficilis; nasals and palatine slits rather long; molar teeth large, 

 actually larger than those of truei and nearly equalling those of difficilis. 



Measurements. Type : Total length, 200 ; tail vertebrae, 93 + ; hind foot, 

 23; ear from notch (measured dry), 25. Skull of type: Greatest length, 

 28.9; basilar length of Hensel, 22; /ygomatic width, 14.5; interorbital 

 constriction, 4.5; interparietal, 10x3; nasals, 10.4; bony palate, 4.2; 

 palatine slits, 5.8 x 2 ; diastema, 8.3; postpalatal length, 10; upper molar 

 series, 4.3; greatest diameter of audital bullse, 6.5. 



Remarks. The relationships of this rather remarkable mouse are 

 clearly with P. truei and P. difficilis. Its short tail * and light color are 

 sufficient to distinguish it from difficilis at a glance, and its enormous 

 audital bullse separate it at once from truei. The external ears are also 

 very large, slightly exceeding those of difficilis as well as of all other 

 species. There is only the one specimen in the collection, in spite of the 

 fact that its habitat is in the state of Vera Cruz, where reasonably 

 thorough collecting has been done. 



*The tail of the type is not quite perfect, having lost the extreme tip, 

 but it is very evident that it was naturally much shorter than that of 



difficilis. 



7 Puoc. BIOL. Sue. WASH. VOL. XVII, 1904. 



