ELASMOBRANOHII. Ill 



Oenus PTYCHODUS, Agassiz. 



Ptychodus polygteus, agassiz. 



Fragments of Ptychodus teeth from tlie Nodule-bed below the 

 Red Crag of Suftblk are preserved in the Ipswich Museum. These 

 have doubtless been derived from the Chalk, and are interesting 

 an account of the rarity of Cretaceous remanie fossils in tiiese 

 deposits. 



Genus RAJA, Linnaeus. 

 Raja clavata, linnmus. 

 ( Thornback.) 

 (Vert. Forest Bed, p. 132, Plate XIX., Figs. 10, 11.) 



Teeth agreeing with those of the living " Thornback " have been 

 recorded from the Weybourn Crag of East Runton (Mem. Greol. 

 Surv. Vert. Forest Bed., p. 132, 1882) and are preserved in the 

 Museum of Practical Geology and in Mr. Savin's collection at 

 Cromer. Agassiz (Poiss. Foss., Vol. III., p. 371) proposed the 

 name of R. antiqua, for dermal defences of Rays found in the 

 Norwich Crag, which agree precisely with those of the livino- 

 R. clavata, he, apparently, thinking it impossible for the Crag 

 species to be still living. These Crag dermal defences are now 

 included with the teeth above noticed in the recent species 

 R. clavata. Dermal defences referable to Raja clavata have been 

 found in the true Coralline Crag of Orford and Gredgrave, in 

 the Nodule-bed below the Red Crag at numerous localities in 

 Suffolk, and in the Norwich Crag at several places in Norfolk. 

 They have also been recorded from the Antwerp Crag and from 

 the Pliocene of Tuscany. 



Teeth of this species have, at present, only been found in the 

 Weybourn Crag of East Runton. 



Now living on the coasts of Europe. 



Raja batis, linn^eus. 

 ( Skate.) 

 (Vert. Forest Bed, p. 131, Plate XIX., Fig. 9.) 

 A number of teeth of this species have been found in the Wey- 

 bourn Crag at East Runton, and like the last are now in Mr. 

 Sarin's collection, and in the Museum of Practical Geology. In 

 the latter there is also a similar tooth obtained by Mr. Clement 

 Reid from the Coralline Crag of Gedgrave. Mr. Lamplugh also 

 has teeth of the same species from the so-called " Bridlington 

 Crag." 



Now living on the coasts of Europe. 



