160 



DEVELOPMENT OF OEGANIC LIFE 



[Ch. IX. 



world in 1854, called Stereognathus* consisting of part of 



lower jaw containing three double -fanged teeth, indicatin 



Natural size. 



Phascolotherium Bucklandi (Owen). (Syn. Didelphis Bucklandi, Brod.) Lower 



jaw, from Stonesfield.f 

 1 The jaw magnified twice in length. 2 The second molar tooth magnified six times. 



Fig. 6. 



a 



b 



JAW OF STEREOGNATHUS, FROM STONESFIELD. 



a. Portion of jaw with three molar teeth from Stonesfield oolite. Natural size. 

 ( Owen's Paleontology, p. 345.) b. Middle tooth of the three contained in the jaw a. 

 (Owen, Ibid., p. 346.) 



an animal small in size, hut \nrvpv than n.nv nf +Tia p/Yntam- 



widely separated from others, one of right half of a lower jaw, of which the 

 the peculiarities in the Thylacotherium inner side is seen. The jaw contains 

 of Stonesfield, which at first induced 

 M. Blainville to refer that creature to 

 the class of reptiles. 



* This generic name was given to it 

 in 1854, by Mr. Charlesworth, who ob- 

 tained it from the Eev. J. P. Dennis, in 

 whose possession it had been for twenty 

 years or more. 



t This figure (No. 5) was taken 

 from the original, formerly in Mr. 

 Broderip's collection, and now in the 

 British Museum. It consists of the 



seven molar teeth, one canine, and three 



incisors ; but the end of the jaw is 



fractured, and traces of the alveolus 



of a fourth incisor are to be seen. With 



this addition, the number of teeth 



would agree exactly with those of a 



didelphis. The fossil is well preserved 



in a slab of oolitic structure containing 



shells of trigonise and other marine 



remains. See Broderip, Zool. Joura. 



vol. iii. p. 



Geol. Soc, November, 1838. 



408. Owen, Proceedings 



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