from the Lias and Oolites. 41 



imbedded in the plates of the test, and have in some measure 

 injured the surface. 



We dedicate this species to M. Michelin of Paris, the distin- 

 guished author of the ' Iconographie Zoophytologique/ as a 

 tribute of gratitude for the valuable collection of Echinodenns 

 he liberally and generously sent us from his unrivalled cabinet, 

 to facilitate our studies of these beautiful forms of ancient life. 



Nucleolites scutatus, Lamarck. 



Since the publication of our memoir on the CASSIDULID^E of 

 the Oolites *, we have received from Professor Deslongchamps 

 and M. Tesson a series of type specimens of Nucleolites scutatus 

 from the Coral Rag of Trouville, Calvados, which we have com- 

 pared with Nucleolites dimidiatus, Phillips, described in that me- 

 moir ; from this comparison it is certain, that our Wiltshire and 

 the Yorkshire Nucleolite, figured by Professor Phillips as N. dimi- 

 diatuSy is the true N. scutatus of Lamarck. This circumstance 

 affords another example of the great importance of comparing 

 all our British Oolitic fossils with those collected from the 

 Jurassic strata of the continent of Europe, before assigning them 

 a position in our catalogues of species. 



Ophioderma Gaveyi, Wright, 1852. PI. III. fig. 1 a-c. 

 Diagnosis. Disc large, upper surface not exposed, under surface 

 with five pairs of heartshaped plates, above which the five rays 

 pass ; the median scutal plates of the rays form a ridge in the 

 centre of each pair of plates ; the mouth-opening is sur- 

 rounded with five pairs of very prominent toothlike processes ; 

 the rays are slender and gently tapering; the central scutal 

 plates on the dorsal and ventral surfaces of the rays are 

 narrow, those on the ventral surface resemble the bodies of 

 small vertebrse deprived of their neural elements. 



Transverse diameter of the body-disc 1 inch and T %ths, trans- 

 verse diameter of the rays at their junction with the disc nearly 

 y^ths of an inch. 



Description. This Sea-star must have been rather abundant 

 in the Liasic sea ; we have seen many fine specimens of it, and 

 numerous fragments of others in the locality where it was col- 

 lected. The body-disc is large and pentagonal, it is composed 

 underneath of ten thin, delicate triangular plates arranged in 

 pairs, each pair forming a heartshaped shield, having an elevated 

 rugose carina down its centre, formed by the 'median clement 

 of the ventral scutal plates which protrudes between each of the 

 two plates forming a pair ; the five shields are otherwise smooth 

 * Annals of Natural Hi*t<>r\. \ol. \\. 



