4 ECHINODERMS OF THE CRAG. 



Fine specimens from the Coralline Crag of Sutton, &c., have been communicated by 

 Capt. Alexander, Mr. Brown of Stanway, Mr. Searles Wood, and Mr. Bowerbank. This 

 species is preserved in most collections ; and specimens presented by the three first-named 

 gentlemen are exhibited in the collections of the Museum of Practical Geology. 



2. Echinus melo ? Plate III, fig. 10. 



Echinus melo, Lamarck. Anim. sans Vert., vol. iii, p. 45. 



— — Agassiz. Monog. Ecbin. Anat. Echinus, p. iii. 



— — Agassiz and Besor. Ann. Sc. Nat., 3d series, torn, vi, p. 365? 



Mr. Searles Wood has communicated the remains of a remarkable urchin of consider- 

 able dimensions, which appeal's to be distinct from any I have seen from the Coralline 

 Crag, whence it is derived. The fragment exhibits a considerable number of the plates of 

 the dorsal surface, with well-preserved portions of two of the avenues. The plates bear 

 few and scattered tubercles, mingled with few and scattered granules. One of the 

 tubercles is slightly larger than the rest, on each plate. The pores are ranked in triple 

 series, ranged at a slight angle of obliquity, and each rank set further apart from its 

 neighbour than is usual. These arrangements approach so nearly to those I have seen in 

 some examples of the true Echinus melo, that until more perfect specimens of the fossil 

 are met with, I place it provisionally under that species. 



3. Echinus Lyellii. Plate I, fig. 5. 



Body a convex, and rather elevated spheroid. Interambulacral areas (centrally) to 

 ambulacrals, as 5 to 2. Ambulacral plates, each with a single primary tubercle, and, to- 

 wards the base, a small secondary one, so that the ambulacral segments are distinguished 

 by the presence of two very regular, rather distant rows of nearly equal close-set tubercles. 

 From the outer or avenue-side of their bosses proceed three radiating ridges to separate the 

 pairs of pores in the avenues. The interambulacral plates are rather high (for the genus) 

 in proportion to their breadth. Each bears from one to three primary tubercles, of which 

 the centre one is largest, (but all are rather small,) and a few scattered miliary granules. 

 The tubercles appear few, in proportion to the extent of the interambulacral spaces, and 

 the larger ones fall into rows, but not so conspicuously marked as the ambulacral rows. 

 The pores are arranged in oblique series of three pairs in each, each pair separated from the 

 others by the radiating ridges already mentioned. The apical disk appears to have been 

 small in proportion to the size of the body. The mouth and under surface has been 

 destroyed. The spines are unknown. 



The only specimen (an imperfect one,) of this very distinct urchin which I have seen, 

 measures -f-f-ths of an inch in height. Although a fragment, it is in good preservation. 

 It was discovered, by Mr. Wood, in the lowest part of the Coralline Crag, at Ramsholt. 



