218 MISS DOROTUEA BATE ON A NEW GENUS 



tliiid moliir. Schlosser gives the nnml)er of roots for tliis tooth 

 as three, hut judging f loiu the alveohis of a specimen of T. platyce])s 

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

 times be two large, transverse roots only. 



The last lower molar in 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 tootli of Leithia and the recent Eliomys, though in the latter 

 there is a more marked constriction immediately below the crown. 



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

 few femorn, 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 tlie 

 Mnscardinidje. 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 Hystricidpe, SciuridtB, and 

 Anomalui'idfe, which have the tibia and fibula free, a charac- 

 teristic of the Muridse and Muscardinidfe is the joining of these 

 two bones for a third or moi'e of their distal portions. It may be 

 woi'th noting that in Rattus {Epiinys), for instance, the fibula 

 at its distal extremity is once more separated though closely 

 adpressed to the tibia. On the other hand, in Eliomys q-icercimis 

 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 thi'ee last- 

 mentioned genera. In Hypnomys the tibia is a stiaighter 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 difterent islands. 



Tiie species from Menorca may be named 



Hypnomys mahonensis, sp. n., 



aiid regarded as the type species of the genus, distinguislied from 

 the Mallorcan species by its greater size and diiterent habitat. 

 Fm-ther diftereuces 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 i-emains of Myotragus and Tesiudo 

 gyninesicus. Some imperfect lacertilian jaws also occurred, and 

 tliese 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 

 gi-oiip '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 



