416 MICROTIN^ 



Remarks. — The skull characters indicate that A. abbotti was 

 highly specialized for fossorial habits; the eyes and external 

 ears, judging from the skull, were smaller than in A. amphibius ; 

 the masseter and temporal muscles appear to have been as in the 

 living species, but the pterygoid internus muscle was more power- 

 ful, with a larger fleshy origin and a smaller and more tendinous 

 insertion. Why the limb skeleton should be smaller in proportion 

 to the head it is difficult to say ; it may be perhaps connected in 

 some way with more terrestrial and less aquatic habits, but it is a 

 feature seen also in the older genus Mimomys. 



Buckland noted the profusion in which the remains of " Water 

 Rats " occurred in the Kirkdale cave, and he sent some of his 

 specimens to Cuvier, who determined them as belonging to the 

 same subdivision of the voles as that containing the existing 

 Water- Vole. But with customary astuteness Cuvier remarked : 

 " cependant si Ton excepte les machoires et les dents, je trouve 

 tous les autres os un pen plus petits, ce qui me fait soup9onner que 

 I'espece n'etoit pas la meme. Ainsi les femurs, les tibia que je 

 possede ne sont pas plus grands que dans le schermauss ... On 

 doit engager les personnes voisines de la caverne, a tacher de se 

 procurer un crane assez entier pour donner les caracteres; ce 

 sera le seul moyen de determiner positivement I'espece." He 

 also notes that a calcaneum and an astragalus figured by Buck- 

 land are respectively a little smaller and a little different in shape 

 from those of the Water- Vole. But it was not until 1910 that 

 evidence of the kind demanded by Cuvier was forthcoming, and 

 then not from Kirkdale, but from the Ightham Fissures. At that 

 time I was unaware of Cuvier's suggestion and so no reference was 

 made to it in my description of A. abbotti. 



Since 1910 I have determined remains of A. abbotti from the 

 following Late Pleistocene deposits : — 



Kent. Ightham Fissures. 



The type and several other tolerably complete skulls of younger 

 individuals; a considerable number of fragmentary skulls, man- 

 dibular rami, and limb bones. 



Yorkshire. Kirkdale Cave, Vale of Pickering. 



1. Part of a skull, a left ramus, and some limb bones (B.M., 

 No. 54). 



2. Fragmentary right ramus, some detached teeth, and a right 

 femur, the specimens figured by Buckland (Rel. Diluv., pi. 11, 

 figs. 1-7; B.M., Egerton Coll.). 



3. Three other mandibular rami, several detached teeth and 

 some Umb bones (B.M., Nos. 35682, 44764, 42357). 



Notwithstanding the fragmentary nature of these remains they 

 seem to be referable to A. abbot li. The postero-lateral palatal 

 pits are large; the mandibular angle is small; the hmb bones 

 are very small and slender, as noted by Cuvier. 

 Devonshire. Kent's Cavern, Torquay. 



1. Anterior part of a skull and part of a left ramus figured by 

 Owen (Brit. Foss. Maram., p. 201, figs. 76rt and b) ; five other rami 



