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. ]S"o. 55 is a typical dark long- 

 tailed house-mouse ; the others are pale desert forms. 



19. MiCBOMYS MYSTACINUS Danf. k Alst. 



d. 64, 65, 66. $. 67. Sumela, 30 mi. S. of Trebizond. 

 1500'. 



" Trapped on hill-side below the fir- woods." — R. B. W. 



20. MiCROMYS SYLVATICUS ARIANUS Blanf . 



S. 30, 34. 2 . 32. Bachtiari Mts., 100 mi. N.E. of Ahwaz. 

 5800'. 



These specimens are coloured very like the South Persian 

 M. s. witherhyi Thos., but have the larger teeth of ariamis. 



21. Calomyscus bailwardi Thos. (Plate XVI.) 

 Abstr. P. Z. S. No. 24, p. 23, Dec. 19, 1905. 



25. 6 . Mala-i-Mir, 70 mi. N.E. of Ahwaz. 4300'. 10 April, 

 1905. B.M. No. 5.10.4.68. TyjK. 



Calomyscus. 



A member of the Cricetince, or biserial-toothed Muridse, 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 IST, American Pei^omyscus, 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. 

 Bullae 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 charactei'istic of Cricetus and its 

 allies. 



* Madagascar excepted. 



