174 Mr. Broderip on some Fossil Crustacea and Radiata. 



the bed to be a member of the lias, between the alum shale of Yorkshire, and 

 the lias of the west of England. He considers the lower part of the sand, repre- 

 sented in Mr. de la Beche's section, to be the marlstone of William Smith ; and 

 the bed of grey marl to be the representative of the alum shale of Yorkshire. 



Ophiura Egertoni. 



Oph. radiis tereti-subulatis, articulis superne subtrilobatis, disco sub-piano, subpentagono, 

 rotundato*. 



Mus. Cole.— Egerton. PI. XII. fig. 5, 6, G». 



This species approaches very near to Ophiura texturata, nor is it at all improbable that the 

 living Ophiura may sometimes rest on the remains of its ancient fossil congener ; for Lord Cole and 

 Sir Philip Egerton dredged up the recent animal from the trawling ground at Lyme. 



Some of the specimens have been weathered to a nicety, and these display in a beautiful manner 

 the articulation and structure of the animal. Others are surrounded and clogged with the matrix, 

 and this is only noticed that the different appearances may not lead to a supposition that there is 

 among them more than one species, viz., that which I have named after the indefatigable Sir Philip 

 Egerton, who worked the specimens out with his own hand. Since the above was written Lord 

 Cole has found some very small individuals. 



Ophiura Egertoni differs from Ophiura Milleri of Professor J. Phillips, inasmuch as, among other 

 differences, the disk of the latter is lobated, according to the figure given in the " Geology of the 

 Yorkshire coast," Plate XIII. fig. 20. There is no description ; but there is authority for con- 

 sidering the figure to be correct, though it is stated to have been drawn from separate parts f. 



Genus Cidaris. 



Several specimens of this genus are among the collection submitted to my 

 observation. They appear to me to be the same species in different stages 

 of growth, and may be identical with that figured as an Echinus by Mr. de la 

 Beche, in the Trans. Geol. Soc. vol. ii, PI. IV., 2d series. I have not seen 

 the specimen, but the proportion of the mamilla, or ball of the spine joint, as 

 given in the figure, is larger than that of the same part in those before me. 



Cidaris Bechei. 



Cid. testa subglobosa, mamillis parvulis, spinis elongatis, aculeatis. 



Mus. Cole. — Egerton. 

 I have named this cidaris after my friend Mr. de la Beche, whose geological works are too 

 extensively known and valued, to require more than an allusion to them on my part. 



* The reader must remember that the external surface is abraded, in the specimen from which 

 the description and principal figure are taken ; and that in its natural state, the disk had probably 

 a more rounded form. 



t I have not been able to procure a sight of the fossil Ophiura, in the museum of Mr. Matthew 

 Wright of Bristol, from the lias on the banks of the Severn in Gloucestershire, and the cast does 

 not convey sufficient information for comparison. Professor Sedgwick has been good enough to 

 forward to me three specimens of Ophiura, which he had procured from Miss Anning. They 

 appear to me to be all Ophiurce Egertoni, 



