Dr. 0. I. Forsyth Major — Rodents of W. Mediterranean. 505 



{A. terrestris, A. amphibms, etc.). There is a further agreement of 

 A. Henseli with several members of the subgenus Piiymys, as at 

 present understood, in some cranial characters. The skull is 

 arched longitudinally, with backward shelving of the occipital ; it 

 is throughout rather high, but especially so the subcylindrical 



x8 



fl cl 



m^ m2 mj 



Arvicola {Tyrrhenicola) Henseli, Maj. 



From the ossiferous breccia of S. Giovanueddu n. Iglesias (S.W. Sardinia). 



Upper view of the left lower molars (eularged, x 8). 



p. posterior transverse loop ; c.t. closed triangles ; a. anterior loop. 



brain-case. The group of recent species of Pitymys, which agree 

 with the fossil in these characters, are represented by Arvicola 

 incertus, Gerbe nee Selys (South-eastern France), A. ibericus, Gerbe 

 (Spain), A. lusitanicus, Gerbe (Portugal), A. nebrodensis, Mina- 

 Palurabo (Sicily), a new species from the province of Lecce (South- 

 eastern Italy), A. Thomasi, Barr.-Ham. (Montenegro), and a new 

 species (A. Savii, Winge nee Selys) from Greece. 



A. Henseli has, howevei*, several cranial and dental characters of 

 its own which have induced me to place it in a separate subgenus 

 (Tyrrhenicola). The nasals slope away anteriorly, more than in any 

 other known species ; tliey are also much longer. The whole of 

 the anterior facial portion of the skull is remarkably elongate, and 

 comparatively narrow ; accordingly the foramina incisiva, which are 

 provided with sharp margins, are remarkable for their length. 

 The superciliary ridges unite in the middle line to form a sharp 

 longitudinal crest. In the posterior basal portion of the skull the 

 bones are crowded together, the mesopterygoid fossa is short and 

 rather narrow, the posterior palatal fossae very deep. The tympanal 

 bullee are comparatively small. Some of the preceding characters 

 had already been pointed out by Cuvier,^ as well as by Hensel,^ who 

 both had fragmentary crania from Sardinia at their disposal. 



The incisors, as well as the molars, are weak when compared with 

 the size of the skull. 



All the molars are rootless throughout life. A peculiar feature of 

 the molars, in which they approach the voles of the Upper Pliocene 

 (Mimomys), which, however, are rooted, consists in the dentine 

 spaces being more or less confluent with each other, so that, strictly 

 speaking, there are no absolutely closed triangles. This character 

 has been much exaggerated in the figures of the vole from Sardinia 

 published by Hensel," more especially in the two anterior lower 

 molars. It is a general feature of the molars of all young voles. 



1 Op. cit., p. 205. 



' Op. cit., pp. 471, 472, 475. 



^ Op. cit., pi. XXV, figs. 3a, b. 



