46 On the Fossil Teeth (^/Myliobatis. 



remarkable for the great relative breadth of their median 

 teeth, as shown botli by the figures and the following 

 measm-ements : — 



The lateral teeth are likewise comparatively broad and 

 irregularly hexangular, and the coronal contour is flat. 



A connected series of median teeth (no. P. 1508 «), of 

 which each measures 0*040 by 0"0045j is also probably refer- 

 able to this species, and testifies to the dimensions to which 

 it sometimes attained ; aiid the specimen shown in fig. 13, 

 though somewhat fragmentary and belonging to the opposing 

 dentition, may possibly be similarly determined. 



The specific name of latidens suggests itself as appropriate 

 for the form thus imperfectly recognizable ; and, so far as can 

 be judged from teeth alone, it may be regarded as allied both 

 to M. toliapicus and to the small fossil with narrower lateral 

 teeth from the Upper Miocene of Aquitaine described by 

 Delfortrie as M. dimorphus'^. 



Range. Bracklesham Beds. 



With regard to the two species, M, gyratits and M. jugalis, 

 ascribed by Agassizf to the London Clay of Sheppey, I am 

 unable to make any definite statement, not having examined 

 the types. It appears, however, almost certain that the 

 specimens are abraded fragments of the early dentition of one 

 or other of the species defined above. 



EXPLANATION OF PLATE I. 



Fig. 1. I^ower dentition of Myliohatis Dixoni. (No, P. 4467 c.) 



Fig. 2. Ditto. (No. P. 4.38.) 



Fig. 3. Ditto. (No. P. 1508 a.) 



Fig. 4. Ditto. (No. 25641.) 



Fig. 5. Lower dentition of Mi/liobatis striatiis. (No. P. 1507 a.) 



Fig. 6. Ditto. (No. P. 1507 6.) 



Fg. 7. Ditto. (No. P. 3049 a.) 



* E. Delfortrie, Actes Soc. Linn. Bordeaux, vol. xxviii. (1871), p. 227^ 

 pi. xi. fig. 39. 



t L. Agassiz, o^j. cit. vol. iii. pp. 323, 324, pi. xlvi. figs. 1-3, pi. xlvii 

 figs. 13, 14. 



