218 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
vertebree from ? to $; the hind feet, $ to }; the ears are small ($ or less), 
thin, and papery, and appear slightly hairy, but may have lost much of their 
fur in the aleohol. The soles have but five perfect tubercles, with a minute 
or rudimentary sixth one. 
Several skulls (as Nos 10038,-‘402°) which we have extracted from 
alcoholic specimens furnish occasion for no further comment than that they 
are strictly of the Pedomys type of dentition, and smaller than those of 
austerus, in correspondence with the inferior size of var. curtatus ; No. 12169 
measuring only 0.90 by 0.56, although it is perfectly adult. 
Suscenus PITYMYS, McMurt. 
Arvicola sp., AUCTORUM. 
= Psammomys, LECONTE, 1829 (pinetorum), (not of Rueppell). 
= Pitymys, MCMuRTRIE, 1831 (same type). 
= Pinemys, Lesson, 1842 (same type). 
Cuars.—Below medium size; body cylindrical and otherwise shrew-like 
in closeness and glossiness of pelage; tail very short—less than the head, 
little more than the hind foot; ears small, mostly concealed, sparsely pilous, 
with flat edges, and border of meatus plane in front; feet small, both five- 
tuberculate; fore-claws not shorter than hind-claws; palms more than half as 
long as soles; teats only four, inguinal; skull relatively broader than usual; 
muzzle short, very blunt; nasal branch of intermaxillary reaching beyond 
ends of nasals; distance from tips of lower incisors to apex of descending 
process no greater than distance from same point to back of condyle; first 
under molar with only one external closed triangle and two internal ones; no 
spur on last triangle of second upper molar; back upper molar with only one 
exterior triangle and a posterior trefoil. 
This section, perhaps the most strongly marked among American 
Arvicole, nevertheless agrees exactly with Pedomys in the dentition (the 
three diagnostic teeth, viz., front under and middle and back upper, being 
the same), and likewise shares with Pedomys the number and position of the 
mamm~e and plantar tubercles. In general cranial and external characters, 
however, it is quite different; Pedomys being in these respects much like 
Myonomes. From Chilotus, which has the same characters of the upper 
molars, it differs in having a less number of lateral triangles on the front 
under molar, and particularly in the construction of the ear, as detailed else- 
where; besides, in other external characters, Chilotus is more like Myonomes. 
The great size of the fore feet and their claws, the small hind feet, and very 
short tail are strong peculiarities. 
