W2 Lankester — On a new Fossil Fish. 



named by him, I have little hesitation in stating my conviction 

 that none of these are well founded. Sir Philip Egerton (Quart. 

 •Journ. Geol. Soc, Lond., vol. xvi.) considers two of them founded 

 on imperfect data — Clieirolepis curtus being from an imperfect 

 specimen of Gh. Cmnmingice ; the seeming larger size of the head 

 and obliquity of the mouth being occasioned by " dislocation of 

 the cranial bones," and the apparent shortness of the trunk and 

 smaller tail being owing to the " concealment of the nape, by some 

 of the dislocated members, and mutilation of the extremity of the 

 upper lobe of the tail." The only other distinctive characteristic 

 given by McCoy, is the tuberculated scales. This, it seems to 

 me, might probably have been occasioned by the nature of the matrix. 

 Gheirolepis macrocephalus, founded on its proportionately larger head 

 is shown by Sir Philip to be merely Ch. Trailli, — a squeeze having 

 "thrown down one ramus of the lower jaw, and forced the pec- 

 toral arch from its normal position;" hence the seemingly larger 

 head. Clieirolepis velox is, however, considered by Sir Philip suffi- 

 ciently marked to constitute a new species. It is described as 

 differing from the others in its smaller head, more slender body, and 

 larger fins, — all three characteristics, as already stated, are very apt to 

 vary from the state in which they may be preserved ; and on com- 

 paring a well-marked specimen of Ch. Cummingice, in my possession, 

 in which, however, the head is imperfect, with the figure of Ch. 

 velox, given by McCoy in the " British Palaeozoic Fossils," they cor- 

 respond so exactly in every respect, except that in my specimen the 

 depth of the body is, perhaps, slightly greater, that I cannot but 

 believe them identical. The position, size, and form of the fins, even 

 to their minutest details, are exactly the same in both. 



The species described by Agassiz are undoubtedly good, and well 

 marked. I am not so well acquainted with the characteristics of 

 Cheiroleph Trailli, as of the other two species, but in these latter, at 

 all events, the scales are quite sufficient to distinguish them from 

 one another. 



In Cheirolepis Cummingia the scales are small, rhomboidal, and 

 quite smooth, as in Acanthodes Mitchelli and Ischnacanthus gracilis. 



In Cheirolepis uragus they are small and rhomboidal, with five or 

 six delicate converging strige on the anterior edge of the ioner 

 surface, somewhat like those of Cheiracanthus microlepidotus and 

 Diplacanthus longispinus, but smaller than those of the latter. 



In Cheirolepis Trailli they are small, rhomboidal, and have each 

 a very prominent, sharp, oval, lengthened tubercle in the middle, 

 parallel, with the oblique posterior border. 



Rbswaxlie, Fokfar. 



IV. — On Bidtmaspis, a. new Genus of Cephalaspidian Fishes. 



By E. Ray Lankester, Esq. 



(PLATE VIIL, Figs. 4-8). 



niHF specimen which I intend briefly to notice was obtained 



JL by Dr. Grindrod, of Malvern, about two years since, from 



