ELASMOBKANCHII. 103 



Antwerp Crag which he named Hannover a aurata ; and in 1873 

 Prof. Steenstrup (K. D. Vidensk. Selsk. Forhandl., No. 1) showed 

 that these bodies agreed with the branchial appendages of the 

 Basking Shark. Afterwards Prof. Van Beneden (Bull. Ac. Roy. 

 Belg., Ser. 2, Vol. XLIL, p. 294, 1876) referred them to the 

 genus Selache. 



It seems highly probable that these specimens, and also the 

 vertebrae from the Antwerp Crag described by M. C. Hasse 

 (Natiirl. Syst Elasmobr. Besond. Theil, p. 241, 1882) belong to 

 the same species as the clasper-spines found in the English Crag, 

 and might be included in the recent species until they can be 

 shown to be distinct. 



The Basking Shark is now living in the Arctic Seas, and 

 occasionally conies as far south as Portugal (Gunther, Cat. 

 Fishes, B. M., Vol. VIII., p. 394, 1870). 



Genus CARCHARODON, Miiller & Henle. 



Many teeth belonging to this genus have been exhumed from 

 the various Crag pits of Suffolk ; but while there has been a 

 general agreement as to the generic affinities of these fossils, the 

 specific determinations have not been so satisfactorily settled. It 

 has long been felt that several of the fossil species named by 

 Agassiz would be found to be parts of the same species, arid the 

 memoir by M. R. Lawley (Studi Comp. Pesci, Carcharodon, &c., 

 1881) has helped in this correlation.* At present only two species 

 of Carcharodon can be recognised in the British Crags ; and this 

 agrees with Lawley 's recognition of the same two forms in the 

 Italian Pliocene deposits. 



CAKCHAEODON MEGALODON, AGASSIZ. 

 PLATE IX., FIGS. 13a, b. 



The present species was proposed by Agassiz for the large 

 shark's teeth from the Miocene of Malta, and North America, and 

 similar specimens from the English Crag were referred to the same 

 species. The occurrence of C. megalodon in the Crag was first 

 recorded by Mr. Charlesworth (Mag. Nat. His., Ser. 2, Vol. L, 

 p. 225, 1837) ; subsequently the species was described by Agassiz 

 (Poiss. Foss., Vol. III., p. 247, 1843). The Maltese and American 

 specimens have strongly serrated edges, but the English ones are 

 usually devoid of serrations, and this has led to the supposition 

 that the latter represented a distinct form of Shark. The English 

 Crag examples are, however, always much water-worn, and although 

 it is very rare to find specimens which shows traces of the serration, 

 yet there are one or two such in the Museum of Practical Geology, 

 and there is every reason for thinking, that all these large Shark's 



* For full synonymy, reference should be made to Mr. A. Smith Woodward (Cat. 

 Foss. Fishes, B. M., Part i, p. 411 and onwards, 1889.) 



