Mr. F. M^Coy on some new Mesozoic Radiata. 401 



that, the radiating lamellae are little more than half the num- 

 ber, are much thicker and almost perfectly smooth. In num- 

 ber and thickness of the lamellse it more nearly approaches tht3 

 common A. helianthoides (Gold.), but differs in their compara- 

 tive smoothness and the more equal size and quadrate form of 

 the cells, &c. 



Common in the inferior oolite of Dundry and Bath, 



[Col. University of Cambridge.) 



Astrcea helianthella (M'Coy). 

 Sp. Char. Corallum forming large depressed turbinate masses 

 (generally from 2 to 5 inches in diameter and 9 lines to 2 inches 

 high) with faint concentric wrinkles below, crossed by very 

 minute radiating strise ; upper surface flat, covered with small, 

 subequal, polygonal cells (diameter, or from centre to centre, 

 varying from 1|^ to 2 lines) with rounded boundaries and very 

 deeply excavated centres ; lamellse about thirty-eight, eight or 

 nine of which reach the centre, of moderate, nearly equal thick- 

 ness, slightly rugged. 



This fine species is abundant in the lower oolite, and seems to 

 be constantly distinguished from the A. helianthoides (Gold.) of 

 the coralline oolite by its smaller and more equal cells, more nu- 

 merous lamellse and flatness of the masses, particularly of the 

 stelliferous surface. 



Common in the inferior oolite of Dundry. 



{Col. University of Cambridge.) 



Bider astrcea agariciaformis (M^Coy). 



Sp. Char. Corallum forming large foliaceous expansions; cells 

 about li line in diameter, arranged in rows, the cells of each 

 row half their diameter apart, the rows nearly twice their dia- 

 meter apart ; the cells are radiated by about twelve lamellse 

 from a depressed cellulose centre ; they increase in number 

 towards the margin, and the greater number take a straight 

 course in two opposite directions to unite with the nearest star 

 of the adjoining row on each side (giving the corallum the 

 appearance of being strongly striated in one direction as in 

 Agaiicia). 



This coral is very like the lower part (natural size) of Gold- 

 fuss's figure of his Astraa fiexuosa from the cretaceous rocks of 

 St. Peter's Mountain. It is most usual to find the lower side 

 exposed by a sort of rough section, in which the cells project like 

 the so-called genus Montastrcea. In the section the small con- 

 necting vesicular plates are seen. 



Common in the coral rag of Upware, near Cambridge. 

 (Col. University of Cambridge.) 

 Arm. <Sf Mag. N. Hist. Ser. 2. Vol ii. 28 



