54 MESSRS. HANCOCK AND ATTHET ON 



HI. — Notes 0)1 various Species of Ctenodus obtained from the 

 Shales of the Northumberland Coal Field. By Albany Han- 

 cock, F.L.S., and Thomas Atthey. 



The curious genus Ctenodus was founded by Agassiz on a single 

 specimen of a palatal tooth procured from the compact coal of 

 Tong, and preserved in the Leeds Museum. It was named C. 

 cristatus, and was described in his " Recherches sur les Poissons 

 Fossiles," where it is tolerably well figured. He mentions two 

 other species, under the respective names of C. alatus and C. 

 Rohertsoni — the former from Ardwick, the latter from Burdie 

 House ; but we can find no specific description of either,* though 

 there is an account and figure of the microscopic structure of C. 

 Robertsoni ; but these do not assist us at all in determining its 

 specific identity. So far as we are able to ascertain, C. cristatus 

 is, then, the only described species of this genus belonging to 

 the Carboniferous system. We are, therefore, gratified to find 

 ourselves in a position to add several new species of Ctenodus to 

 the fauna of our Coal-Measures. 



During a long-continued examination of the shales in the neigh- 

 bourhood of Newcastle we have not only procured divers spe- 

 cimens of Agassiz's species, but have also obtained five or six 

 others, all of which are distinguished by well-marked characters. 

 It is our intention to give in this communication short descrip- 

 tions of the whole of them, reserving for some future occasion 

 more lengthened details of their characteristic features. In the 

 first place, however, a few remarks may be made respecting the 

 fishes to which this beautiful armature belonged. 



Agassiz thought they were Placoids ; and so they were deemed 

 to be for several years, until Hugh Millerf obtained and described 

 similar palatal plates attached to the roof of the mouth of a small 

 fish belonging to the Old Red Sandstone, which had previously 

 been described under the generic appellation of Dijiterus by 



* Fi-om a remark in Agassiz's " Monogr. des Poiss. Foss du Vieux Gresrcuge," it appears 

 Ihal both species are inedited. 



t See " Footprints of tlif Creator." p. fi-J. 



