412 Mr. F. M'Coy on some new Mesozoic Radiata. 



tion, forming two alternating rows of moderately large, per- 

 forated, crenulated primary tubercles with many intervening 

 blunt granules ; interambulacral spaces twice as wide as the 

 ambulacral, with two rows of very large primary tubercles, 

 only four to five in a row, the smooth bases of which are ver- 

 tically confluent (not separated by rows of granules), two ver- 

 tical rows of small granules between the tubercles. 



The only species this can be confounded with is the H. Thur- 

 mani (Ag.), which it resembles in its depressed form and very 

 few large tubercles, and in the small size of the tubercles on the 

 interambulacral spaces, but in this species the ambulacra widen 

 more and the primary tubercles on them are larger ; while each 

 of the primary interambulacral tubercles in that species is sepa- 

 rated from the next above and below by several rows of granules, 

 while they are confluent, so to speak, in the present. 



Rare in the great oolite of Minchinhampton. 



(Col. University of Cambridge.) 



Diplopodia (M'Coy), n. g. 



Gen. Char. Depressed, subpentagonal from the pro- 

 jection of the ambulacral spaces; two rows of 

 primary tubercles both on the ambulacral and 

 interambulacral spaces ; ambulacral rows of two 

 pairs of pores in the upper half, of one pair in 

 the middle and becoming again compound, of 

 two or sometimes three pairs of pores towards 

 the mouth. 



This genus is distinguished from Diadema, to 

 which it is most allied, and Pedina, by the former 

 having uniformly one pair of pores in a row, and the 

 latter having uniformly three pairs of pores in a row. 

 The following species and the D. subangulare (Ag.) 

 are the types of the genus, which is only known in 

 the oolites. 



Diplopodia pentagona (M'Coy). 



Sp. Char. Pentagonal, depressed, having an average diameter of 

 9 lines, with a height of 4 lines ; interambulacral spaces one- 

 third wider than the ambulacral at middle ; two distinct rows 

 of primary tubercles in each interambulacral space, surrounded 

 by few small granules, and having on the outer side near the 

 mouth five or six secondary tubercles one-third the size of the 

 primary, forming a short single irregular row scarcely reaching 

 the middle ; ambulacral spaces with two rows of primary tu- 

 bercles nearly equalling those of the interambulacra in size, 



Ambulacrum 

 of Diplopodia. 



