ORDER II 



MARSUPIALIA 



33 



tubercle. The M also sometimes have but one point, owing to reduction. 

 The three tubercles of the upper M often develop secondary tubercles. 



Subfamily 1. Amphitheriinae Owen. 



Lotver I's almost vertical, lower M's tuber culo- sectorial with strong, two-rooted 

 falonid. Coronoid process broad, angle of the mandible rounded, downwardly directed. 

 Articulation situated low down. Behind C there are nine to twelve teeth. 



Amphitherium Blainville [Thylacotherium Val.) (Fig. 51). Middle Jura of 



England. . A jaw found in 1818 was assigned to marsupials by 



Cuvier, and to reptiles by Blainville. 



Amphitijlus Osborn. Same horizon and locality. 



Feramus, Leptocladus Owen. Upper Jura (Purbeck) ; England. 



Fig. 51. 



Amphitherium prevosti Blv. Great Oolite ; 

 Stonesfield, near Oxford. Exterior aspect of left 

 half of lower jaw. a, Vi ; ^i ^/l- (After Owen.) 



Fig. 52. 



Amblotheriiim soricinwn Owen. Upper Jurassic of 

 Purbeck, England. Right half of lower jaw. A, i/i. 

 B, s/i- (After Owen.) 



Subfamily 2. Amblotheriinae Osborn (Stylacodontidae Marsh). 



M gradually becoming a single cone, single-rooted. C with a single roof, 

 coronoid process slender, angle of lower jaw not sharply accentuated. I forwardly 

 inclined, P^ and P^ larger than M. Behind C eleven to twelve teeth. 



Amblofherium Owen (Fig. 52). Upper Jura (Purbeck); England. . 



Probably the upper M of Peralestes Owen belong here, which have besides 

 protocone, metacone and paracone also parastyle and metastyle. 



Peraspalax Owen and Achyrodon Owen. Upper Jura (Purbeck) ; England. 



Phascolestes (Dryolesfes) Marsh. Upper Jura ; Wyoming. 



Laodon and Asthenodon Marsh. Same horizon and locality. 



Stylodon Owen {Stylacodon ? Marsh). Upper M. Kurtodon Osborn (Fig. 53). 

 Upper Jura (Purbeck) ; England. 



Subfamily 3. Paurodontinae Marsh. 



M two-rooted, indistinctly tuberculo-sectorial, with minute secondary tubercles. 

 Lower jaw short and massive. Not more than seven teeth following C. Jura of 

 Wyoming. 



Paurodon Marsh. 

 VOL. Ill 



Apparently 



3.1.4.3. 



like most Placentalia. 



