263 

 SPECIFICALLY UNDETERMINED SPECIMENS. 



The following specimens from the Middle Purbeck group of Durdle- 

 stone Bay, Sivanaye, are referred by Owen to the present genus. 



47770. The two terminal extremities and the impression of the 

 (Fig.) middle portion of a mandibular ramus of a small form. 



Figured by Owen, op. cit. pi. iii. fig. 20. 



Beckles Collection. Purchased, 1876. 

 47797. Fragments of a mandible, showing the bases of some of the 



teeth. Same history. 



48396. Small fragment of a mandibular ramus, showing one true 



molar. Same history. 



47769. The greater portion of a mandibular ramus of a very small 



(Fig.) form, showing some broken cheek-teeth. Figured by 



Owen, op. cit. pi. iii. figs. 16, 16 a. Same history. 



Family DASYURID^E. 



Dentition : I. |, C. \, Pm. + M. various. There are never more 

 than three premolars in each jaw ; the lower true molars are with- 

 out an inner cingulum, and are either multicuspidate or differentiated 

 into a blade and talon, the latter being never simply secant in all the 

 teeth of the series and always smaller than the hinder lobe of the 

 blade ; the upper true molars are cusped and either subquadrangular, 

 or triangular with an inner tubercle. The hind feet have the 

 hallux without a claw, and generally either rudimentary or absent, 

 while the four outer digits are well developed. 



Subfamily PASTURING. 



Dentition : Pm. + M. not exceeding ^, and of relatively large 

 size; the premolars are differentiated- from the true molars; the 

 lower incisors are in contact ; the lower true molars are differentiated 

 into a bilobed blade, which frequently has an inner cusp, and a 

 talon which is usually tubercular, but may be secant *in one tooth 

 of the series, in which case it is always smaller than the hinder 

 outer cusp of the blade ; the upper true molars are triangular with 

 a well-marked inner tubercle ; and the fourth premolar when well- 

 developed is preceded by a milk-tooth. 



The upper true molars are simpler than in the PerameUdce, the 

 elongated inner column of the latter forming a rounded tubercle, 



