196 MR. E. T. NEWTON ON THE VERTEBRATE [May 1 894, 



Myodes lemmus. (Norwegian Lemming.) PI. XT. fig. 9. — Two 

 mandibular rami and a single cheek-tooth are all the remains which 

 can be definitely referred to this species. The front cheek-tooth 

 has 4 inner and 3 outer angles (or 5 and 4, if the very slight angles 

 of the small anterior prism be counted), the prisms having the 

 open lax arrangement distinctive of the Norwegian lemming. 

 The jaws, when perfect, must have been about the same size as 

 the largest of those referred below to M. torquatus. Myodes lemmus 

 is known as a Pleistocene species ; at the present day it is living 

 in the Scandinavian peninsula and in Russian Lapland. 



Myodes torquatus. (Arctic Lemming.) PI. XL fig. 10. — Twelve 

 mandibular rami, of different sizes, more or less perfect, and for the 

 most part with their teeth in place, represent this species. These 

 rami are intermediate in size between Microtus amphibius and 

 M. agrestis, and the front cheek-tooth has the 5 outer and 6 inner 

 angles characteristic of the Arctic lemming. Among the rodent limb- 

 bones alluded to below several distinct sizes may be distinguished, 

 between those which agree best with Microtus agrestis and those re- 

 ferred to M. amphibius. The largest of them are much smaller than 

 those of M. amphibius, and may belong to the present species or to 

 Myodes lemmus; but on comparison with the skeletons of M. tor- 

 quatus in the British Museum they are found to be stouter, and the 

 femora and humeri have distinctly larger heads. Myodes torquatus 

 occurs in Pleistocene deposits in England and on the Continent, 

 but is at the present day a purely Arctic animal, living, according 

 to Coues and Allen, in Arctic America, Greenland, and corresponding 

 latitudes in the Old World. 



Microtus (=Arvicola) glareolus. (Bank- Vole.) — To this species 

 are referred more than a dozen lower-jaw rami, the front cheek-teeth 

 of which have the characters of M. glareolus (4 outer and 5 inner 

 points). Two of these rami belonged to aged animals, the teeth 

 being strongly rooted. The smallest of the arvicoline limb-bones 

 among these fossils are shorter and stouter than those belonging to 

 recent examples of this species, and it is possible that some of those 

 which come near to M. arvalis may belong here. Microtus glareolus 

 has been found in the Forest Bed, in Caves, and in Pleistocene 

 river-deposits ; it is now living in Britain and throughout Europe ; 

 it extends southward to the Apennines, and northward to within 

 the Arctic Circle. 



Microtus ( = Arvicola) amphibius. (Water- Vole.) — About twenty 

 lower-jaw rami, very perfect, and several portions of skulls, as well 

 as many incisor teeth, pelvic bones, femora, tibiae, humeri, ulnae, and 

 radii, are without any doubt referred to this species — the front 

 lower cheek-teeth having the characteristic; pattern, namely, 5 inner 

 and 4 outer angles. Microtus amphibius has been found in Pleisto- 

 cene deposits, and possibly also in the Forest Bed ; it is now living 

 throughout Europe as well as in Great Britain, and extends east- 

 ward through Siberia. 



