OF EXTINCT MUSCARDINE RODENT. 



219 



measurements can be given, but the following are a few. The 

 length of the nasals is about 18 mm. in the single example in 

 which these bones are completely preserved, and the interorbital 

 width of the frontal s is 8 mm. The base of the outer wall 

 of the infraorbital canal measures 6 mm., and the incisive 

 foramina are approximately 8 mm. in length. In the type 

 specimen (PI. I. fig. 1) the complete row of left upper cheek-teeth 

 is almost 10 mm. in length, this measurement being 14 mm. in a 

 corresponding example of Leithia, and barely 7 mm. in one of 

 Eliomys lusitanicus. In //. mahonensis the width of the palate 

 between the first molars is not quite 6 mm., in Leithia it is little 

 more, being 6*5 mm. 



The length of the lower cheek-teeth series is about 10 mm. ; 

 as already mentioned the length of their roots is very variable : 

 in one specimen having teeth with moderately worn crowns 

 (B.M. M 11673, PI. I. fig. 7) the first molar has a crown-width 

 of 2*5 mm. with a root-length (measured from' the crown-surface 

 to root-tip) of almost 5 mm. In the third molar in the same 

 specimen the greatest length of root is 3 mm., the large posterior 

 root attaining an antero -posterior width of 1*5 mm., while the 

 antero-posterior length of the crown is 2 '5 mm. In an example 

 of a left lower second molar (B.M. M 11676, PI. I. fig. 9) with a 

 less worn crown than the above the crown-width is 2 mm., and 

 the greatest root-length 3 mm. 



It is proposed that the species from Mallorca be known as 



HYPNOMYS MORPHEUS, Sp. 11., 



characterised by its smaller size and different habitat from 

 H. mahonensis. The few specimens of jaws and limb-bones by 

 which it is represented were obtained from cave-deposits in 

 Mallorca, and were found associated with remains of Myotragus, 

 and in one case with a few mandibular rami and limb-bones of 

 Apodemus, which still occurs plentifully in the island. In size it 

 appears to agree with the larger forms of Glis. The type speci- 

 mens (B.M. M 11695), consisting of the anterior portion of the 

 skull with the incisors and right molars and two mandibular 

 rami, are believed to have been associated and fell apart on being 

 separated from the earthy matrix in which they were preserved. 

 The base of the outer wall of the infraorbital canal measures 

 5 mm., and the antero-posterior length of the molar row is 6 mm. 

 The length of the lower cheek-teeth series is 8 mm. In the 

 upper incisor (B.M. M 11696) shown in fig. 10 (PI. I.) the antero- 

 posterior width is 2*5 mm. while the thickness is 1*5 mm. ; in a 

 specimen of the lower incisor the antero-posterior width is 2 mm., 

 with a thickness of barely more than 1 mm. 



The greatest length of a right tibia, wanting its proximal 

 epiphysis, is 41 mm., the distal 18 mm. of which are joined to the 

 fibula. A femur has a total length of 55 mm., that of a right 

 ulna being 36 mm. 



