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Show 1882.] MR. O. THOMAS ON RODENTS FROM PERU. 101 *uina 2 2 2 2 2 2 2 Total 1. mammas. 6 4 6 6 8 8 10 Nr. of adult females examined. 1 8 6 1 2 1 (type 7 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 Muridae. The following Table gives the number of mammae found in a few of the best-known Sigmodontes not included in the present collection :- Pectoral pairs of mammtc. Ochetodon mexicanus, Be Sauss. ... 1 Hesperomys (Ehipidomys) sumi-chrasti, Be Sauss 0 H. (Vesperimus) leucopus, Raf. ... 1 H. (V.) michiganensis, Aud. § Bach. 1 H. (Oryzomys) couesi, Alst 2 H. (Oalomys) bimaculatus, Waterh. 2 Sigmodon hispidus, Say §- Ord ... 3 We thus see that the number of mammae 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 doubtl, is, so far as its mammae are concerned, very distinct from any of the other New-world Muridae in having no less than 5 pairs, the largest number found in this group. 1. LEPUS BRASILIENSIS, L. a (juv.). Cutervo, 9000', Feb. or Mar. 1879. 2. ECIIINOMYS SEMISPINOSUS, Tomes, P.Z. S. 1860, p. 265. «. <5 (imm.), Tumbez, sea-level, June 1876. " In the reeds (Canna brava) on the banks of the river." [Mus MUSCULUS, L. A. Callacate, 4800', April 1879. This specimen bad a large HJstrus-\av\a. in the flesh just above the root of the tail (See C. O. Waterhouse, Proc. Ent. Soc. 1881, p. xxii).] 3. H O L O C H I L U S (NECTOMYS) APICALIS, Peters, Abhandl. Akad. Berl. 1860, p. 152. Hesp. cephalotes, Desm., Tomes, P. Z.S. 1858, p. 548 (nee Desm.). a. Chirimoto, 5400', Jan. 1880. b. Huambo, 3700', April or May 1880. c, d (juv.). Tambillo, 5800', Feb. 1878. Dimensions, in inches :- Head and body. Tail. Hind foot. A. o* • • 7*5 9*0 1'96 b. <S.. 8*4 10-1 2*05 In the paper quoted above, Prof. Peters described a large Guaya- 1 Mon. N. Ara. Eod. p. 32, 1877- Forearm and hand. 1*96 2*15 Ear-conch, length. •68 •65 Muzzle to ear. 1-58 1*77 |
