274 MAEStTPIALIA. 



M. 2298. Cast of the hinder portion of a mandibular ramus. The 

 original is from the Lower Jurassic Slate of Stonesfield, 

 Oxfordshire, and is preserved in the Museum at Oxford. 

 It is the type specimen, and is figured by Prevost in the 

 'Ann. Sci. Nat.' vol. iv. p. 389, pi. xviii. fig. 2; by 

 Buckland in his ' Bridge-water Treatise,' pi. ii. (as 

 Didelphys) ; by Owen in the ' Trans. Geol. Soc.' ser. 2, 

 vol. vi. pi. v. fig. 3, in his ' British Fossil Mammals and 

 Birds,' p. 44, fig. 16, in his ' Odontography,' pi. xcix. fig. 2, 

 and in his ' Mesozoic Mammalia ' (Mon. Pal. Soc.), pi. i. 

 fig. 21 ; and by Phillips in his ' Geology of Oxford and 

 the Valley of the Thames,' p. 233, diagram no. 77. The 

 jaw contains four premolars and six true molars. 



Presented ly Prof. Prestwich, 1884. 



36822. Part of a left mandibular ramus, containing the last premolar 

 and five true molars, provisionally referred to this species. 

 The true molars are of the type of those of Amllotherium 

 the length of the space occupied by the five teeth of this 

 series being 0,005. Morris Collection. Purchased, 1862. 



Genus AMBLOTHERIUM, Owen l . 



Including : Peraspalax, Owen 2 . 



Peralestes (Phascolestes), Owen 3 (in parte). 



Dentition : I. ?, C. ?, Pm. J, M. ~^. The lower incisors are 

 spaced, the lower true molars may have a small inner cusp to the 

 blade 4 , the anterior lobe of the blade of the latter is of moderate 

 height, and pm. 3 and pm. 4 are slender. 



Amblotherium soricinum, Owen \ 



This is the type species ; the hinder lower true molars have a minute 

 inner cusp to the blade, and that series of teeth did not apparently 

 exceed seven in number ; the length of the space occupied by the 

 first six of these teeth is 0,005. 



Hob. Europe (England). 



1 Mesozoic Mammalia (Mon. Pal. Soc.), p. 29 (1871). 



2 Ibid. p. 40. 3 fad. p . 35. 



4 Owen regarded the presence of this cusp as distinguishing Peraspalax from 

 Amblotherium; it is, however, distinctly present in the hinder molars of 

 A. soricinum. 



8 Op tit. p. 29. 



