410 Mr. Pi M'Coy on some new Mesozoic Radiata. 



having the elliptical smooth spaces in both the interambulacral 

 and ambulacral areas j the present is also a larger and more co- 

 nical species. 



Not very uncommon in the coralline oolite of Calne, Wiltshire. 



{Col. University of Cambridge.) 



Echinus diademata (M'Coy). 



Sp. Char. Conoidal (diameter of one specimen 10 lines, height 

 6 lines), base abruptly flattened, subpentagonal from the pro- 

 minence of the ambulacra, which are slightly convex and one- 

 half the width of the interambulacra ; interambulacra having 

 a concave, smooth, narrow space in the middle of their upper 

 portion, the middle of each half bears one row of about twelve 

 large primary tubercles, their wide smooth disc surrounded by 

 a circle of minute granules, numerous granules being scattered 

 in the intervening spaces ; only two or three very small se- 

 condary tubercles on the outside of the base of the primary 

 rows ; ambulacra with two rows of large primary tubercles each, 

 with many small, irregularly placed intervening granules ; 

 three oblique pairs of pores in each row ; ovarian and ocular 

 plates as in the genus generally. 



The two rows of large tubercles in each area, with the very 

 minute intervening granules, distinguish this species from its con- 

 geners. It is most closely allied to the E. fallax and E. serialis 

 (Ag.), but is well distinguished by the almost complete absence 

 of secondary tubercles as well as the greater size of the primary 

 ones, and the more pentagonal form of the disc, in which it ap- 

 proaches the E. eoccavatus (Gold.), from which it equally differs 

 by the above characters. 



Occurs in the coral rag of Malton and in the great oolite of 

 Minchinhampton. 



{Col. University of Cambridge.) 



Arbacia inflata (M'Coy). 



Sp. Char. Oblate-spheroidal (diameter 6 lines, height 4£ lines), 

 margin of the base tumid, rounded ; ambulacra flat, depressed, 

 slightly less than half the width of the interambulacra, the 

 pores forming very narrow rows of one pair each, the space 

 between the lines of pores with four to six very unequal, irre- 

 gular rows of small granules ; interambulacral spaces tumid, 

 with a slightly impressed, narrow, smooth line down the mid- 

 dle of each; each interambulacral space contains about six- 

 teen rows of minute tubercles, of which the two middle rows, 

 or that bordering on each side the sutural line, are largest ; 

 under the lens the tubercles are distinctly arranged in trans- 

 verse rows, eight on each interambulacral plate, touching each 



