TRICOXODONTID.I. 259 



47764. Portion of the left ramus of the mandible, showing pm. 2 and 



{Fig.) the first three true molars. Figured by Owen in the 



* Mesozoic Mammalia,' pi. iii. figs. 9, 9a; there is no trace 



of m. 4. Same history. 



47767. Part of the left ramus of the mandible, containing pm. 4 

 {Fig.) and m. i. Figured by Owen, op. cit. pi. iii. figs. 10, 10 a. 



Same liistory. 



M. 19. Cast of the right ramus of the mandible, showing pm. 3, pm. 4, 

 and the four true molars. The original (woodcut, fig. 39) 

 is preserved in the Museum of Practical Geology, Jermyn 

 Street, and is described and figured by Willett in the 

 ' Quart. Journ. Geol. Soc' vol. xxxvii. p. 378 (woodcut) : 



Fi?. 39. 



Triconodon mordca\ — The right ramus of the mandible ; from the 

 Purbeck of Swanage. \. 



it was suggested in the description that the first of the 

 four trilobed teeth might be mm. 4 ; this is, however, dis- 

 proved by the large size of the two preceding teeth, which 

 must be pm. 3 and pm. 4, since pm. 2 is shown by other 

 specimens to be a much smaller tooth ; the length of iIITT 

 + ^^^2 is 0,006, and that of i^TT + 1^172 + ^^^3 0,009. 



Presented by H. Willett, Esq., 1881. 



M. 3750. Cast of the right ramus of the mandible, showing the 

 homologous teeth to those of the preceding specimen. The 

 original is in the collection of Mr. Willett. 



Made in the Museum. 



The following specimens are referred by Owen to Triacanthodon serrula 



(47763 being the type), but apparently present no characters by 



ivhich they can be distinguished from the present species. 



M. 47763. A slab of Purbeck limestone, containing the left ramus 



{Fig.) of the mandible and some other imperfect bones. The 



mandible has been figured by Owen in the ' Mesozoic Mam- 



