Mr. F. M'Coy on some neiv Mesozoic Radiata. 415 



The symmetry of the two ends separates this species at a 

 glance from its congeners. 



Not uncommon in the inferior oohte of Bridport. 

 {Col. University of Cambridge.) 



Dysaster suhringens (M^Coy). 



Sp. Char. Nearly orbicular, faintly subpentagonal by the pro- 

 jection of the interambulacra, depressed, but the height rather 

 more than half the length (length 1 inch 1 line, width the same, 

 height 7 lines) ; dorsal surface evenly convex ; oral surface 

 radiatingly undulated by the shallow concavity of the am- 

 bulacral spaces, and the gentle gibbosity of the interambu- 

 lacra, the posterior one most prominent ; each interambulacral 

 plate seems on the oral face nodulous in its middle, forming 

 two obsolete rows of nodules on each ridge ; mouth nearly 

 central ; anus a little above the posterior margin ; three an- 

 terior ambulacra meeting at the centre of dorsal surface, very 

 narrow, gradually enlarging towards the margin, posterior pair 

 double the width of the anterior ones, short, curved, meeting 

 immediately over the anus. 



If carefully observed, this can only be confounded with the D. 

 ringens (Ag.) of the Swiss oolites, but it is at once distinguished 

 by its greater gibbosity (in which it exceeds the allied D. Voltzii) 

 and in the less prominence of the ridges on the under side, which 

 however exceed those of the latter species ; the disproportionate 

 narrowness of the three anterior ambulacra, as in the D. ringens, 

 separates it from the D. Voltzii and D. Eudesii (Ag.). 



Not uncommon in the inferior oolite of Dundry and Leck- 

 hampton. 



{Col. University of Cambridge.) 



Nucleolites planulatus (M^Coy). 



Sp. Char. Rotundato-subquadrate, length and width equal, much- 

 depressed, upper surface flattened, margin obtusely rounded 

 (length and width 1 inch 3 lines, depth 6 lines) ; ambulacra 

 wide, the pores of each pair in the petalloid part connected 

 by a long distinct furrow ; anal sulcus deep, extending from 

 the vertex to the anal margin which it slightly indents ; gra- 

 nulation very minute. 



This species from its great depression need only be compared 

 with the N. planatus (Romer, Versteinerungen des norddeutsch. 

 Oolithengebirge), but it is wider than that species and the upper 

 surface flatter, and I find on comparing specimens of the two 

 species that the present is completely distinguished by its wide 



