NORTH STAFFORDSHIRE COAL FOSSILS. 243 



hollow rays. The caudal fin has a short terminal prolon- 

 gation covered with scales. This curious appendage is rarely 

 preserved. The contour of the head is not well shown 

 in any of our specimens. The surface ornament of the 

 head is of a granular character. It has two elongated 

 jugular plates, beautifully ornamented with fine, undulating, 

 nearly parallel ridges. The walls of the air bladder were 

 ossified, and this part is frequently preserved in a fossil 

 state. 



Position and locality : Not rare in the Deep mine 

 ironstone ; more rare in the Chalky mine, Knowles, and 

 Brown mine ironstones ; fine specimen in the Cheadle coal- 

 field. 



FAMILY CTENODODIPTERINI, HUXLEY. 

 GENUS CTENODUS, AGASSIZ. (Ref., Poiss. Foss., vol. iii.) 



The genus Ctenodus was established by Agassiz on a 

 single specimen of a tooth which is now preserved in the 

 Leeds Museum. Several species are enumerated by Agassiz, 

 but only one species was described (G. cristatus). More 

 recently * Mr. Atthey has described several new species 

 from the Northumberland coal-shales. Much interest is 

 attached to this genus in consequence of the discovery, a 

 few years ago, of the extraordinary fish named Ceratodus 

 Fosteri, a fish now living in several of the rivers of Australia, 

 which is said to have teeth identical with those of the 

 extinct genus Ceratodus from the Triassac rocks, and to be 

 still more closely allied to the genus Ctenodus from the 

 Carboniferous formation. The dental apparatus is said to 



* Ann. Nat. Hist., ser. 4, vol. 1, p. 77. 



