218 



MISS DOROTHEA BATE ON A NEW GENUS 



third molnr. Schlosser gives the number of roots for this tooth 

 as three, but judging from the alveolus of a specimen of T.platyceps 

 in the British Museum (M1627) it appears that there may some- 

 times be two large, transverse roots only. 



The last lower molarin Hypnomys has three roots, two anterior 

 slender ones and a large, backwardly projecting posterior one. 

 This condition is very similar to that obtaining in the correspond- 

 ing tooth of Leithia and the recent Eliomys, though in the latter 

 there is a more marked constriction immediately below the crown. 



Limb-bones. — Very little of the skeleton was obtained, but a 

 few femora,, a tibia, and fragmentary portions of humeri and 

 other bones, chiefly from a Mallorcan cave-deposit, show characters 

 which also indicate that the genus should be included in the 

 MiiscardinidaB. The ulna is very similar to that of Eliomys, as is 

 also the femur, except that the third trochanter seems to be 

 slightly less prominent and less sharply separated from the great 

 trochanter. As contrasted with the Hystricidaa, Sciurida?, and 

 Anomaluridse, which have the tibia and fibula free, a charac- 

 teristic of the Muridas and MnscardmidaB is the joining of these 

 two bones for a third or more of their distal portions. It may be 

 worth noting that in Rattus (Epimys), for instance, the fibula 

 at its distal extremity is once more separated though closely 

 adpressed to the tibia. On the other hand, in Eliomys quercinus 

 the tibia and fibula continue completely ankylosed at their distal 

 ends, and it is with this latter that the Balearic specimens agree, 

 as Leithia likewise does in this respect. These bones are joined 

 for more than a third of their total length in the three last- 

 mentioned genera. In Hypnomys the tibia is a straighter bone 

 with a less well-developed cnemial crest than in Eliomys. 



The above are the chief characters of all the Balearic specimens, 

 and it will only be necessary to add a brief note and a few 

 measurements in the two species from the different islands. 



The species from Menorca may be named 



Hypnomys mahonensis, sp. n., 



and regarded as the type species of the genus, distinguished from 

 the Mallorcan species by its greater size and different habitat. 

 Further differences would probably be apparent were a larger 

 amount of material available. All the specimens were obtained 

 from fissures in the Miocene limestone, and were in one or two 

 instances associated with remains of Myotragus and Testudo 

 yymnesicns. Some imperfect lacertilian jaws also occurred, and 

 these have been very kindly examined by Mr. G. A. Boulenger, 

 F.R.S. : they prove to be those of a Lacerta of the viridis-ocellata 

 group and a species of Chcdcides. Although representatives of 

 both these occur commonly in the Mediterranean region, neither 

 are found in Mallorca or Menorca at the present day. 



Owing to the fragmentary state of the specimens not many 



