64 MESOZOIC RADIATA. 



rounded posterior margin ; granulation of surface very minute 

 and close. 



This resembles the N. clunicularis (Smith sp., Clypeus lobatus, 

 Flem.) in the long, deep, narrow posterior sulcus, extending quite 

 from the vertex j but is wider and more quadrate, the base having 

 exactly the form of the N. scutatus (Lamk.) ; from the latter it 

 differs in the strong sulcus uniting the pores as in most of the 

 genus, and from both species it is distinguished by its pointed 

 elevated apex and the straight declivity of the posterior side. 

 ' Common in the cornbrash near Weymouth. 



{Col. University of Cambridge.) 



Nucleolites aqualis (M'Coy). 



Sp. Char. Subquadrate, very much depressed (length 9 lines, 

 width S~ lines, height 4 lines), evenly convex above, very con- 

 cave beneath; vertex central; anal fissure deep, wide, and sharp- 

 edged, extending from the vertex to the margin, which however 

 is scarcely indented ; ambulacra very broad, petalloid part with 

 the pores of each pair connected by a deep sulcus ; the two 

 anterior interambulacral spaces are each at the margin only 

 the width of an ambulacral space less than the width of the 

 lateral interambulacral spaces. 



This species is much depressed, but not flattened above ; the 

 ambulacra equal or even slightly exceed those of the N. latifrons 

 (Ag.) in width ; but the species is distinguished from all of the 

 genus by the near equality in size of the interambulacral spaces, 

 the two anterior ones, usually so small, being only the width of 

 one of the ambulacra less than the lateral ones in width. 



Great oolite near Minchinhampton. 



Inferior oolite near Castle Ashby. 



{Col. University of Cambridge.) 



Clypeus excentricus (M'Coy). 



Bp. Char. Orbicular, depressed (length and width each 3 inches 

 11 lines, height 1 inch 2 lines), posterior end slightly produced 

 and sinuate ; anal sulcus deep ; vertex nearly one-fourth of the 

 length nearer the posterior than the anterior end ; mouth small, 

 a little excentric towards the anterior end; ambulacra very wide; 

 granulation as in the C. patella. 



This species differs from the C. sinuatus (Park.) by the vertex 

 being so much nearer one end than the other, and from the C. 

 patella by its much greater depression. 



Abundant in the inferior oolite of Leckhampton. 



{Col. University of Cambridge.) 



