Mr. F. M*Coy on some new Mesozoic Radiata. 411 



other without intervening granules, but between one plate and 



the next above or below (or between the rows) there are a few 



minute granules, generally arranged in one or at most two 



irregular rows. 



Distinguished from the A. pilos (Ag.) by its more depressed, 

 inflated form, rounded margin of the base, the outer* row of am- 

 bulacral tubercles not being largest, and the greater number of 

 tubercles in both arese, as well as the central smooth line of the 

 interambulacra ; the A. granulosa (Miinst. sp.) is much more de- 

 pressed, has the ambulacra wider and more convex, the interam- 

 bulacra more deeply divided, and a much greater number of tu- 

 bercles in the transverse rows, which latter are separated by very 

 numerous crowded granules. 



Not uncommon in the upper greensand of Cambridge. 



{CoL University of Cambridge.) 



Acrosalenia rarispina (M^Coy). 



Sp. Char. Spheroidal, depressed; ambulacra flat, slightly flex- 

 uous, with two rows of tubercles which towards the base are 

 large, mammillated and perforated ; interambulacra three times 

 the width of the ambulacral spaces, primary tubercles very pro- 

 minent, nearly twice their diameter apart, placed alternately, 

 but scarcely more than two tubercles in each vertical row ; each 

 tubercle surrounded by a ring of blunt granules, and between 

 one tubercle and another numerous similar granules are scat- 

 tered. 



I think the position of the anus and the plates of the vertex 

 agree with that division of the genus to which the A. aspera be- 

 longs, but a little adhering siliceous matrix in each of the speci- 

 mens before me prevents my being quite certain. The ambulacra 

 being a little undulated also approximates it to the A. aspera, 

 but it is a much rarer species, and easily distinguished by the 

 singularly small number and great distance of the primary tu- 

 bercles, and the quantity of intervening granulation. Diameter 

 4 lines, height 3^ lines ; sometimes larger. 



Rare in the great oolite of Minchinhampton. 



[Col. University of Cambridge.) 



Hemicidaris confluens (M'Coy). 

 Sp. Char. Depressed (average diameter 9 lines, height 5 hues) ; 

 ambulacra undulating, upper third narrow, gradually widen- 

 ing to the mouth ; the upper portion bears very minute 

 crowded tubercles, which gradually increase in the wide por- 



* By " outer " I here mean, adjoining the ambulacra, without intending 

 to deny that the mesial line may be the true exterior. 



