Recent Fo/e^ r/ Me Mi crol us nivalis Group. 101 



tail, Avhile in seven (including the type) the tail is distinctly 

 bicolor throughout. 



Microtus lebrunii (Crespou). 

 (Synonymy under subspecies.) 



Geographical distribution. — South-eastern France (Depart- 

 ments of Gard and Basses- Alpes). 



Characters. — Like Microtus nivalis, but smaller (hind foot 

 less than 20 mm. ; condylo-basal length of skull in adults 

 less than 28 ram.) and paler, the tail always pure white 

 throughout ; the back a light grey without conspicuous 

 brownish suffusion. 



Remarks. — This species, although described more than 

 sixty years ago, has remained of very doubtful status until 

 within a few months. Mr, Charles Mottaz, of Geneva, 

 Switzerland, has recently visited the Departments of Gard 

 and Basses-Alpes in the interests of the British Museum, 

 and, thanks to his successful work, it is now possible to form 

 some definite opinion as to the animaFs relationships. 



Microtus lebrunii lebrunii (Crespon). 



1844. A\_rvicold]lehrunii, Crespon, Fauue M^ridiouale, i. p. 77. 

 1857. Arvicola nivalis, b. Arvicola leucurus, Blasius, Saugethiere 

 Deutschlands, p. 359 (part.). 



Type localitij. — Neighbourhood of Nimes^ Gard, France. 

 Altitude about 550 feet. 



Geographical distribution. — Known only from the type 

 locality. 



Characters. — Back a clear, very pale smoke-grey, without 

 evident wash of wood-brown. Skull with audital bullae 

 small and flattened, noticeably dill'erent in both form and 

 relative size from those of Microtus nivalis ; other cranial 

 characters as in M. nivalis, except for the smaller general size 

 of the skull; teeth rather smaller than those of J/, nivalis, 

 the anterior loop of the first lower molar resembling that of 

 M. nivalis aquitanius. 



Measurements. — Adult male, no. 5519 {Mottaz) : head 

 and body 122 mm.; tail 66 ; hind foot 18-8; ear 14. Skull: 

 condylo-basal length 27-1 (ca.) ; zygomatic breadth 15 (ca.) ; 

 interorbital constriction 4-6; occipital deptii (median) 7'4; 

 nasal 8 ; diastema 8*2 ; mandible 18 ; maxillary tooth-row 6*4; 

 mandibular tooth-row 6*2. 



Remarks. — The typical form of Microtus lebrunii is easily 

 recognizable by its small size, pale colour, and flattened 



