524 | MR. OLDFIELD THOMAS ON [ Dec. 12, 
When the difficult Mus musculus group comes to be worked 
out these specimens will be of the greatest value, but they cannot 
well be determined at present. No. 55 is a typical dark long- 
tailed house-mouse; the others are pale desert forms, 
19. Micromys mystacinus Danf. & Alst. 
3. 64, 65, 66. 2.67. Sumela, 30 mi. 8. of Trebizond. 
1500’. 
“Trapped on hill-side below the fir-woods.”—A&. B. W. 
20. MiIcROMYS SYLVATICUS ARIANUS Blanf. 
6. 30, 34. 2. 32. Bachtiari Mts., 100 mi. N.E. of Ahwaz. 
5800’. 
These specimens are coloured very like the South Persian 
M. s. witherbyi Thos., but have the larger teeth of arianus. 
21. CALoMYSCcUS BAILWARDI Thos. (Plate XVI.) 
Abstr. P. Z. 8. No. 24, p. 23, Dec. 19, 1905. 
25. ¢. Mala-i-Mir, 70 mi. N.E. of Ahwaz. 4300’. 10 April, 
1905. B.M. No. 5.10.4.68. Type. 
CALOMYSCUS. 
A member of the Cricetine, or biserial-toothed Muride, of 
which the only recent Old World * members hitherto known have 
been the Cricetus group and the South African Mystromys. Most 
nearly allied to the N. American Peromyscus, with which it shares 
the possession of only five cusps on the anterior upper molars. 
External form as in Peromyscus, but the tail bushy terminally, 
as in many Gerbilles, to which the pallid colour also gives a 
resemblance. Ears large. Fur soft. Feet of normal length and 
structure; soles naked except just under the heels; sole-pads six, 
the posterior one far back, separated from the others. Tail long, 
pencilled, the single specimen with a peculiar double tuft of white 
hairs at a point two-thirds along it, which may indicate the 
presence of a special gland, or, more probably, be merely due to 
an accidental injury. 
Skull, as compared with that of Peromyscus, low, flat, and 
rounded, the shape of the brain-case recalling that of a dormouse. 
Bulle low, little developed. Palatal foramina comparatively small. 
Coronoid process of mandible long, considerably overtopping the 
condyle. Incisors smooth. Molars brachyodont, thin, pattern 
very similar to that found in Peromyscus, but even more simple ; 
the cusps low, and the valleys between them shallow, and without 
any trace of supplementary intermediate ridges. First upper 
molar with only five cusps and without any trace of that dupli- 
cation of the anterior cusp so characteristic of Cricetus and its 
allies. 
* Madagascar excepted. 
