348 MICROTIN^ 



the structure of 711^, the structure of the auditory bulla?, and the 

 characters of those parts of the skull immediately under the 

 influence of the temporal muscles indicate, of course, that 

 it is very widely removed from Chionomys. These and 

 many of the other characters described above show that this 

 vole cannot be referred to any genus hitherto known among 

 living forms. On the other hand, in dentition, palate, and jaw 

 structure it agrees so closely with Dolomys, known previously 

 only from fragmentary fossil remains obtained from the late 

 Pliocene and Pleistocene deposits of Hungary, that I am com- 

 pelled to refer it to that genus. 



In palate and tooth structure it makes a very near approach 

 to D. milleri, the older of the two Hungarian fossil species ; the 

 only important difference is that the teeth of the recent species 

 possess cement, whereas those of the fossil lack it. The develop- 

 ment of cement in the molars of voles is a progressive character ; 

 its presence in one species and absence in another, is not a 

 difference of generic importance. 



tGenus : 12. APISTOMYS Mehely. 



1913. Evotomys Ehik, Foldt. KozL, 43, p. 7. Not of Coues. 



1914. A'pistomys Mehely, Ann. Mus. Nat. Hangar., 12, p. 203. 



Genotype. — Apistoniys coronensis Mehely. 



Range in time mid space. — Known only from the Pleistocene 

 (" Zweite interglaciale Periode ") of Hungary. 



Characters. — Differing from Dolomys chiefly by its broader 

 palate and the peculiar form of the ;h^ ; the differences scarcely 

 of generic value. 



Palate essentially as in Dolomys and Mimomys, but strik- 

 ingly broad, its least width opposite m^ considerably greater 

 than the antero-posterior length of that tooth; the posterior- 

 median sloping septum very short and broad. 



Alveolus of incisor crosses from the lingual to the labial 

 side of the mandibular ramus below the posterior root of mj 

 according to Mehely (though his figure, op. cit., Taf. vi, fig. 7, 

 scarcely bears this statement out). 



Cheek-teeth in adults furnished with two roots each ; the 

 anterior root of m^ with two points and obviously a compound 

 of the anterior root proper and of the third or central root found 

 as an independent structure in Dolomys and some species of 

 Mimomys. Surfaces of fangs channelled by vertical grooves, 

 which continue the furrows formed by the cement spaces beyond 

 the limits of the crowns of the teeth. No cement present in 

 the re-entrant folds. Enamel pattern of 7n^, m^, m, ^^^ ''^3 ^^ 

 in normal voles; outer salient angles of m^ reduced in size; m' 

 with three salient angles on each side, nearly as in D. episcopalis, 



