180 PROCEEDINGS OF THE SCIENTIFIC ASSOCIATION. 
Fig. 10. Nucula schomburgki, right valve, exterior. 
., 11. „ vieta, right valve ; magnified. 
„ 12. ,, baccata, left valve, interior. 
„ 13. Periploma orbicularis, left valve, interior. 
„ 14. Lithodomus bipenniferus, right valve, interior. 
„ 14 a. „ exterior. 
„ 15. Hyalea ventricosa ; a lower valve, & upper valve. 
,, 16. „ digitata ; a upper valve, 1) lower valve. 
„ 17. Purpura trinitatensis. 
„ 18. Metula lintea. 
,, 19. Pleurotoma miranda. 
[N.B. — The figures are all of the natural size, except where it is 
otherwise specified.] 
II. On a Heterocercal Fish found in the Blue Lime- 
stone Series of the Laventille Hills. By R. J. 
Leckmere Guppy, F.L.S., F.G.S., etc. (PI. VIII.) 
In a paper on the Blue Limestone of the Laventille Hills 
(Proc. Scient. Assoc. Thin,, 1877, p. 109), I referred to the 
discovery of a fish in one of the beds of the series. I had 
not then seen the specimen, but it has since come into my 
possession, and is now exhibited to the Association. It con- 
sists of part of the vertebral column with the tail-fin of a 
heterocercal fish. There are about thirty vertebras present, 
and the rays of the tail are about fifteen in number. There 
are traces of fine needle-like spines extending backward from 
the vertebrae near the tail. The length of the specimen is 
nearly six inches (15 centimetres) ; the anterior portion is 
nearly straight, the posterior part slightly curved. The 
thickness of the stoutest vertebrae is 5 millimetres ; they 
are nearly all of the same dimensions up to the origin of 
the caudal fin, whence they rapidly taper off to its extremity. 
The specimen came from the Piccadilly quarry on the east 
side of Portofspain. It is exposed on the surface of a thin 
