110 PISCES. 



MyLIOBATIS CO TUMIDENS, S. WOODWARD. 



Mr. Smith Woodward (Cat. Foss. Fishes, Brit. Mus., Part i, 

 p. 119, 1890) has given the name M. tumidens to some mediau 

 dental plates from the Eed Crag Nodule-bed preserved in the 

 British Museum ; but it is not quite certain that they belong to 

 this genus, the ends being abraded. " The coronal contour is 

 sharply raised in the middle, as in M.jugosus, Leidy, differing 

 only from the latter tooth in the greater relative breadth of the 

 rounded elevation." 



Genus iETOBATIS, MtQler & Henle. 



Elongated dental plates, havinjj the ends curved down, and 

 thus showing unmistakably that there were no lateral denticles, 

 are referred to j^tobatis. Such plates have been found in the 

 Nodule-bed below the Bed Crag at Waldringfield, Woodbridge, 

 and elsewhere in Suffolk, and are to be seen in the Museum of 

 Practical Geoloey, the British Museum, and other collections of 

 Crag fossils. They have doubtless been derived from the Eocene. 



Genus RHINOPTERA, MiiUer & Henle. 

 (ZYGOBATIS, Agassiz.) 



Ehinopteea Woodwabdi, agassiz. 



Agassiz (Poiss. Foss., Vol. III., p. 329) proposed the name of 

 Zygobatis Woodwardi provisionally for a number of isolated dental 

 plates, from the Norfolk Crag, in the collections of Messrs. Buxton 

 and Woodward which he thought more likely to belong to this 

 genus than to Myliobatis. Since then all dentary plates of 

 Batidss found in the Crags have been put under the name Zygo- 

 batis Woodvmrdi, which has been said to occur in the Coralline, Eed 

 and Norwich Crags. Reasons have already been given for thinking 

 that none of the plates from the Coralline and Eed Crags can be 

 referred to this genus and species, and for the present it is retained 

 for the Norwich Crag dental plates described by Agassiz, which 

 seem to be extremely rare, the few fragments in the British Museum 

 (P. 1524) being the only examples with which I am acquainted, 

 and these are far from being satisfactory. 



