346 Messrs. Hancock & Atthey on Reptile- and Fish-Bemains 



XLV. — Notes on the Remains of some Reptiles and Fishes 

 from the Shales of the NortJiumherland Coal-field. By 

 Albany Hancock, F.L.S., and Thomas Atthey. 



[Continued from p. 278.] 



[Plates XIV., XV., XVI.] 



Rhizodus Hihherti^ sp., Agassiz. 



The teetli of tliis species have not yet been found in the 

 shales of our neighbourhood ; but large scales Avhich appear to 

 belong to it are not by any means uncommon at Newsham 

 and Cramlington. They are rarely found perfect ; sufficient 

 examples have, however, been obtained to enable us to identify 

 them with the scales of i?A^^06?(<si7^iier<^ described by Dr. Young 

 in vol. xxii. p. 599 of the ' Journal of the Geological Society.' 

 The largest we have seen measures three inches in diameter ; 

 they usually appear quite thin, and are of an irregularly 

 rounded form with the front margin a little flattened, the pos- 

 terior a little produced, and the sides only slightly arched. 

 The surface is marked with numerous sharp concentric lines 

 of growth and minute, close, radiating stria3, requiring a good 

 lens to show them. There are also a few distant delicate 

 ridges, extending from the centre to the anterior border. 



Such scales are undoubtedly in an imperfect condition. 

 When complete, they are considerably thicker, and the under 

 surface has a smooth bony appearance, exhibiting nevertheless 

 decided concentric lines of growth, a subcentral elongated 

 boss, and numerous small pits, particularly on the posterior 

 portion, which, however, we have never seen in a good con- 

 dition. On the posterior or exposed area there are a few ob- 

 scure, irregular, radiating ridges, which are rendered still more 

 indistinct by the granular tubercles that are scattered over the 

 surface. The smaller scales, which are usually about one inch 

 and three-quarters long and scarcely one and a half inch wide, 

 have all the characters of the large scales ; but they are ge- 

 nerally more elongated in form, and the minute radiating strise 

 are coarser. 



Besides these scales, several bones have occurred at News- 

 ham, which, from the peculiar surface-sculpture, most probably 

 also belong to this poAverful fish. We were anxious to prove 

 this by comparing them with some authenticated fragment of 

 the bone of Rhizodus showing the surface-ornament, but have 

 failed in our endeavour. Tliey agree, hoAvever, in this respect 

 so well with the descriptions, that we cannot hesitate to assign 

 them provisionally to this species. 



Of the two most remarkable bones of this collection, one 



