102 



FOSSIL OOLITIC ASTERIAD^. 



formed of a series of stout conical spines, set closely together in rows, and inclined in an 

 imbricated manner on each other. The middle ridge is the broadest and most prominent. 



Dimensions. — Diameter of the disc, two inches and a quarter; length of the only com- 

 plete ray, from the intermediate angle of bifurcation, four inches and three quarters. 



Affinities and differences. — In its general outline this Star-fish resembles Uraster Gaveyi, 

 as we at present only know the under surface of that form and the upper surface of 

 Uraster eauinatus it is impossible to make a critical comparison of these Middle Lias 

 Asteriadae. 



Locality and Btratigrapldcal Position. — This Star-fish was collected from the Marl- 

 stone at Bowlby, near Staithes, Yorkshire, and is the only example at present known. It 

 belongs to the rich collection of my friend, John Leckenby, Esq., F.G.S., of Scarborough. 



TROPIDASTER,^ Forties, 1850. 



Body stellate, five-rayed (a vent on the dorsal surface ?) ; rays convex and carinated 

 above, the carina composed of a double series of squaraose plates ; rest of the dorsal surface 

 spinous ; spines simple ; ambulacra bordered by transverse plates, with spiniferous crests on 

 their anterior margins; ambulacral ossicula rather broad, geniculated, pectinated at their 

 inner extremities. (Suckers biserial.) 



A. — Species from the Lias. 



Tropidaster pectinatus, Forbes. PI. Ill, figs. 1, 2, 3. 



Tropidaster pectinatus, Forbes. Memoirs of the Geological Survey of Great Britain, 



Figures and descriptions of Organic Remains, Decade iii, 

 pi. iii, 1850. 



— — Forbes, in Morris's Catalogue of British Fossils, 2d ed., p. 90. 



— — WrigJit. British Association Reports, vol. for 1856, p. 402. 



Description. — My esteemed colleague, the late Professor Edward Forbes, gave so 

 • excellent an account of this Star-fish that I shall quote his description of the same entire. 

 The general aspect of this species, when seen from above, is that of a Uraster, whilst viewed 



1 Tpo/TTts, a keel, and aoriji^, a star. 



