4 



BRITISH FOSSILS. 



two specimens in the Museum in Jermyn Street, which, although 

 very imperfect, gave evidence of another species of the genus Pleuro- 

 pholis, I have recently received from the Rev. John Austen (whose 

 abours in the Purbeck beds are well known to geologists) three ad- 

 ditional specimens of a species of Fleuropholis apparently different 

 from that indicated by the specimens in Jermyn Street. Of these, 

 one, and that the most perfect, belongs to Mr. W. Brodie, of Swanage, 

 and was found by him in the bed numbered 69 in Mr Austen's 

 table of the Purbeck strata ; a less perfect specimen of a larger 

 individual of the same species was furnished by Mr. Lister, of 

 Langton Purbeck, and the third, a smaller one, is from Mr. Austen's 

 private collection. As the specimens in the Jermyn Street Museum 

 are not sufficiently perfect for detailed description, I may here 

 briefly state that my reason for considering them specifically dis- 

 tinct from the subjects of this and the foregoing description rests 

 upon the character of the large scales covering the flanks of the fish, 

 which, in these specimens, are distinctly serrated on the posterior 

 margin. 



Mr. Brodie's specimen, of which a figure is given in the plate, 

 measures three inches and three tenths from the nose to the ex- 

 tremity of the tail ; the head and tail each measure seven tenths 

 of an inch, and the greatest depth of the body is six tenths. These 

 comparative dimensions attest the slender proportions of the fish, 

 and, combined with the small size of the head and the large size of 

 the tail, give evidence of its having been a swift and agile swimmer. 

 The head is narrow, and somewhat pointed at the muzzle, the gape 

 small, and with no traces of teeth discernible. In these respects, 

 and in the relative proportions of its constituent members, it re- . 

 sembles the corresponding parts in the genus Leptolepis. The 

 pectoral fins contain at least a dozen rays; the anterior one is 

 armed with a border of long sharp spines ; the succeeding three or 

 four rays are very strong ; all these have the transverse articu- 

 lations rather distant. The remainder of the fin is composed of 

 smaller bones, not very distinctly preserved. The ventral fins are 

 small, and situated halfway between the snout and the extremity 

 of the tail fin. The anal fin, commencing a little behind the ventral 

 fins, extended almost to the insertion of the caudal fin. The number 

 of rays constituting this organ cannot be ascertained from any 

 of the specimens. The dorsal fin is small in this species, and 

 situated immediately above the anal fin, a position for this fin 

 very unusual in the members of the Lepidoid family, and very 

 characteristic of the genus PleuropJiolis. The base of the upper 



