42 Mr. A. S. Woodward on the 



the largest is given in the accompanying woodcut, fig. 1. 



Fiy.l. 



The crown is deep and the grinding-surface has a slightly 

 arched contour, flattened in the middle. 



Lower Dentition o/ Myliobatis Dixoni. 



No. of Specimen, 

 Brit. Mus. 

 1. P. 4457 c 

 II. 25660 



III. 25620 



IV. 37758 

 V. P. 438 



VI. 25821 

 VII. P. 1508 a 

 Till. 25641 

 IX. P. 4458 



Of these fossils the third was figured by Dixon as the type 

 of a new species, M. contractus, while in the sixth the original 

 surface is preserved — a fact which led the same author to 

 refer it to M. striatus. The so-called M. heteropleurus may 

 also be placed here with considerable certainty, the median 

 teeth of the type specimen measuring 0*022 by 0*0065, and 

 the lateral teeth, so far as preserved, likewise exhibiting the 

 characters of those of M. Dixoni. I have seen no other 

 fossils like this from Sheppey, and, as already stated by 

 Agassiz, his determination of its being derived from the 

 London Clay is hypothetical. 



Range. Barton and Bracklesham Beds. 



Myliobatis striatus^ Agassiz. (PL I. figs. 5-9.) 



1833-43. Mi/liobafis striatus, Agassiz, Poiss. Foss. vol. iii. p. 320. 

 1833-43. Myliohatis punctatus, Agassiz, torn. cit. p. 322, pi. xlvii. 



figs. 11, 12. 

 1837. Myliobatis striatiis, Buckland, Geol. and Min. 2ad edit. vol. ii. 



pi. xxvii. d, tig. 14. 

 1850. Myliobatis irregularis, Dixon, Foss. Suss. p. 199, pi. xi. fig. 15. 

 1850. Myliobatis Edwardsii, Dixon, op. cit. p. 199, pi. xi. tig. 16. 



A specimen of the lower dentition from the Barton Clay, 



