1882. ] MR. 0. THOMAS ON RODENTS FROM PERU. 101 
the various subgenera and species, though the value of this character 
seems never to have been noticed by any previous writer in connexion 
with the arrangement of the Sigmodont Muride. 
The following Table gives the number of mamme found in a few 
of the best-known Sigmodontes not included in the present col- 
lection :— 
Pectoral Nr. of adult 
pairs of Total females 
mammex. Inguinal. mamme. examined. 
Ochetodon mexicanus, De Sauss. ... 1 : 6 
Hesperomys (Rhipidomys) sumi- re 
chrasti, De Sass. ...rs00cceeseres 2 4 8 
H. (Vesperimus) leucopus, Raf. ... 1 2 6 6 
H. (V.) michiganensis, dud. § Bach. 1 2 6 1 
H. (Oryzomys) couesi, Als? ......... 2 2 8 2 
H. (Calomys) bimaculatus, Waterh. 2 2 8 1 (type) 
Sigmodon hispidus, Say § Ord ... 3 2 10 7 
We thus see that the number of mammee gives us an additional 
character by which to separate Dr. Coues’s subgenus “‘Vesperimus ”’ 
from Calomys, the first having only 3, while the latter has 4 pairs. 
Sigmodon also, on whose generic distinction Dr. Coues has cast some 
doubt!, is, so far as its mammee are concerned, very distinct from 
any of the other New-world Muride in having no less than 3 pairs, 
the largest number found in this group. 
1. Lepus BRASsILIEensts, L. 
a (juv.). Cutervo, 9000’, Feb. or Mar. 1879. 
2, Ecuinomys semispinosus, Tomes, P.Z.S, 1860, p. 265, 
a. & (imm.), Tumbez, sea-level, June 1876. 
“In the reeds (Canna brava) on the banks of the river.” 
[Mus muscuuus, L. 
a. Callacate, 4800’, April 1879. 
This specimen had a large (strus-larva in the flesh just above 
the root of the tail (See C. O. Waterhouse, Proc. Ent. Soc. 1881, 
p» xii). | 
3. Hotocniius (NecTromys) APICALIS, Peters, Abhandl, Akad. 
Berl. 1860, p. 152. 
Hesp. cephalotes, Desin., Tomes, P.Z.S. 1858, p. 548 (nee Desm.). 
a. Chirimoto, 5400’, Jan. 1880. 
b. Huambo, 3700’, April or May 1880. 
e, d (juv.). Tambillo, 5800’, Feb. 1878. 
Dimensions, in inches :— 
Head and Forearm ar-conch, Muzzle 
body. Tail. Hind foot. and hand. length. to ear. 
COE 725 9°0 1:96 1:96 68 1-58 
bs" S2. O4 10°1 2°05 2°15 65 1577, 
In the paper quoted above, Prof. Peters described a large Guaya- 
1 Mon. N, Am, Rod. p. 32, 1877. 
