﻿July, 1896.] 



SUBGENUS PHAIOMYS. 



57 



1887. Lasio])odomys Lataste, Annali del Mus. Civ. di Storia Naturale di Genova, ser. 

 2a, Vol. IV, p. 268, 1887. Type Arvicola hranti Radde. 



Geograpliic d'lHtrihutwn of jiipe species. — -'Banks of Tslio Morari and 

 Pankong lakes, "Western Tibet, also between Seh and tlie PankongLake 

 at elevations above 13,0C0 feet." (Blanford.) 



Geographic distri'bution of suhgeniis. — High plateau region of central 

 and southern Asia. Probably does not occur below the Boreal zone. 



Essential characters: 



Palate normal. 



m 3 without closed triangles. 



m 1 normally with 3 to 5 closed triangles and 8 or 9 salient angles, 

 m 3 normally with 2 to 3 closed triangles and 6 salient angles. 

 Mamm;c probably 10. 

 Plantar tubercles, 6. 

 Sole very hairy. 



Claws very long and of abont equal length on all four feet. 

 Fur remarkably long and soft. 



Shull. — The skull of Phaiomys as compared with that of Fedomys is 

 readily distinguished by its very different form. The brain case in 

 Fedomys is high, long, and almost cylindrical, while that of Fhaiomys 

 is short, broad, and flat. The zygomatic arches are more broadly flar- 

 ing in Fhaiomys than in Fedomys^ while the 



ui^per incisors are usually more promiuent. 

 The latter character is, however, inconstant. 



Bony palate. — The bony x)alate is perfectly 

 normal and requires no detailed descri[)tion. 



Enamel pattern in general. — The enamel ])at- so —Enaiad pattern of 



tern (flg. 30) is exactly like that of FedoniySj moiav u^rCa, Aiirro("s (Fhai- 



. ~ omys) itrauchi. (x 5.) 



except that the outer reentrant angles m m o 



are somewhat less developed, while the anterior outer reentrant angle in 

 m 2 usually divides the anterior loop into two closed triangles. These 

 differences, however, are trivial and inconstant. 



Other teeth, — In some of the members of the subgenus the incisors 

 are directed more forward than usual. The character is, as already 

 stated, wholly inconstant. 



Mammw. — There is still doubt as to the normal number of mammai 

 in the subgenus Fhaiomys. Milne-Edwards found only four in a skin 

 of M. mandrianus ; Biichner found six in a skin of 21. strauchi., and ten 

 in a skin of M.fuscus, I am inclined to think that ten will prove to be 

 the correct number.^ In the specimen of 21. fusctis just referred to 

 there were six pectoral mammie, the rest inguinal. 



Feet. — Tlie feet are large and densely haired. The number of tuber- 

 cles on the sole is still a matter of doubt. Biichner records six in both 



^ That Phaiomys probably has a large number of mammfe — at least more than four — 

 was suspected by Lataste, who in 1887 (Annali del Museo Civico di Storia Naturale 

 di Genova, Serie 2a, Vol. IV, p. 270) called attention to the fact that Blyth found 

 ten embryos in a female Alicrotus Ihjthi. 



