670 ON A NEW RAT FROM GUATEMALA. [June 15, 



recently sent by the Society. The trip had been mainly organized 

 to obtain live animals, but it had been a definite part of 

 ■ Mr. Shortridge's duties to collect what study- specimens he could, 

 and these had now been presented to the National Museum by 

 the Society. 



The species was described as follows : — 



OtOTYLOMYS GUATEMALA. 



Thos. Abstr. P.Z.S. 1909, p. 32 (June 15). 



Allied to 0. phylloiis, but considerably larger. 



Fur soft and fine. General colou.r above uniform greyish -brown 

 (rather bi^owner than " mouse-grey ") ; back darkened by black- 

 tipped hairs. Under surface white, not sharply defined laterally, 

 the majority of the hairs white to the roots, but down the centre 

 of the chest and belly many have slaty bases. Ears not specially 

 enlarged, naked, greyish. Hands and feet parti-coloured, the 

 centre of the metapodials slaty-brown, their sides and the digits 

 white ; in 0. j^hyllotis the whole of the hands and feet are white. 

 Tail not so entii'ely naked as in the allied forms, as there are a 

 few scattered hairs along its under surface ; grey above, rather 

 paler below, not contrasted or mottled. 



Skull markedly larger in all dimensions than that of O.jjhyllotis, 

 but showing all the characters used by Dr. Merriam to distinguish 

 that animal from true Tylomys. The brain-case is, however, 

 deeper and the palatal foramina are not so large. 



Molars with a low but -well-marked supplementary cingular 

 ridge running transvei'sely across in front of the anterior cusps, a 

 structure also found in O.phyllotis, but not in Tylomys, nor, so fa^ 

 as I know, in any other genus of Cricetinaj. 



Dimensions of the type, measured in the flesh : — 



Head and body 170 mm. ; tail 161 ; hind foot (s. u.) 28 ; ear 16. 



Skull — greatest length 40-7 ; basilar length 31-5 ; greatesjt 

 breadth 20"5 ; nasals 15 ; interorbital breadth 6*7 ; breadth across 

 parietal ridges 16-2 ; palatilar length 16*6 ; diastema 11 ; palatine 

 foramina S'l X 3"5 ; length of upper molar series 6-8 (in another 

 specimen 7-2). 



Hah. Tucuru, Polochie R., about 50 miles E. of Coban, Guate- 

 mala. 



Type. Adult female. B. M. no. 9.6.11.13. Original number 4. 

 Collected 24 January, 1909, by G. 0. Shortridge, and presented 

 by the Zoological Society. 



This species is at once distinguishable from 0. phyllotis by its 

 larger size, greyer colour, and parti-coloured feet, in which 

 respects, as in its smaller palatine foramina, it tends to approach 

 the members of Tylomys. It is smaller than O.fumeus Allen. 



Mr. Thomas expressed his pleasure that the discovery of so 

 marked a new form had resulted from the dispatch of Mr. Short- 

 ridge to Central America, and hoped that the Society would 

 undertake many such expeditions in the future. 



