Mr. A. S. Woodward on Ccelorhynchus, Agassiz. 225 



attained a length of at least 0*44 m. The superficial longitu- 

 dinal ribs are broad, close, and somewhat flattened, very even, 

 and several times bifurcated. Distally the section is almost 

 circular and the internal cavity very small ; more proximally 

 the cavity enlarges considerably and the section becomes oval. 

 The fossil is evidently distinct from all others yet named, and, 

 presenting well-marked characters, may be provisionally 

 quoted as G. gigas. 



"While, however, the described specimens and those in the 

 British Museum afford no clue to the affinities of the fish 

 bearing the spines under discussion, one small Chalk fossil 

 in the collection of Henry Willett, Esq., F.G.S., in the 

 Brighton ]\luseum, furnishes some slight information upon 

 the subject *. This is the imperfect anterior portion of a small 

 fish-skeleton (no. 99), exhibiting, apparently on the dorsal as- 

 pect, a perfect example of " Coelorhynchus cretaceus " 0*043 m. 

 in length. The portions of endoskeleton preserved show 

 well that they originally consisted of cartilage, calcified 

 merely at the surface, as in Selachians and Chimairoids ; and 

 the particles of the thin film of hard material are not suffi- 

 ciently large to be distinguished by a lens. In front of the 

 fossil are two large fragments, probably to be interpreted as 

 parts of the head ; and close behind is a broad vertical bar, 

 completely separated at a short distance, and very suggestive 

 in every respect of half of the pectoral arch of a shark or 

 Chimeeroid. Immediately above the supposed pectoral arch 

 is the base of the slender spine, having no unornamented 

 inserted portion and directly in contact with a fragment of 

 cartilage. There are no traces of a vertebral column. 



It therefore seems evident that Coelorhynchus is the spine 

 of a cartilaginous fish, that probably occupied a forward position 

 upon the back ; and, if the interpretation of Mr. Willett'a 

 fossil be correct, the genus must pertain either to the sharks 

 or the Chimseroids. The microscopical structure of the fossil 

 accords with this supposition, although somewhat anomalous ; 

 and as the dorsal spines in no true shark, so far as I am 

 aware, are destitute of a smooth inserted base, I would ven- 

 ture to refer the fish provisionally to the Chimeeroids. The 

 extinct members of the latter order do not all possess dorsal 

 spines of the normal type observed in the living Chimcera,a,3 

 shown by Dr. von Zittel's Chimceropsis f ; and the possibility 



• For the opportunity of studying this specimen the writer is indebted 

 to the kindness of Mr. Willett and of Mr. Edward Crane, Chairman of 

 the Brighton Museum Committee. 



t K. A. von Zittel, ' Handbuch der Palseontologie,' vol. iii. (1887), 

 p. 113. 



