CRETACEOUS ECHINODERMATA. 329 
and centrally punctated plates, which alternate at the sides with a smaller row, 
and these are succeeded by smaller ones. 
The extremity of each ray is swollen into a pyriform shape, forming an eye- 
protecting apparatus. ‘The summit of this is formed by very large convex, sub- 
globose punctated plates which correspond to those at the origin of the ray. 
These alternate at the sides with five very large, nearly flat, oblong, similarly 
ornamented plates, which articulate with others half their size, corresponding to 
the inferior row; beneath them are others much smaller, which (with minute 
ossicles) border the avenue, corresponding to the under row. All the plates of 
the bulbous terminations of the arms are much larger than those to which they 
correspond, except the last. 
This is one of the handsomest and most curious of all the fossil star-fishes. 
It is seldom seen perfect. One or two living species of Oreaster have a similar, 
but not equal development of the plates at the extremities of the rays. The spe- 
cimen figured is from Kent, and in the collection of Mr. Catt, who has also an 
example of this species from Sussex. It is also in the cabinet of the Marquis 
of Northampton, Mr. Bowerbank, and Mr. Tennant. 
Oreaster pistilliferus. (Tab. XXT. fig. 15.) 
A species very distinct from those just described, and remarkable for bearing 
towards the circumference of the disc five elongated, conical, nearly smooth 
rounded spines or prolonged tubercles ; their summits obtuse, round and slightly 
swollen ; their bases much but regularly dilated. The ossicula of the arms are 
nearly equal and regularly arranged in longitudinal series. Each ossicle is trans- 
versely somewhat shuttle-shaped, rather narrow, tumid in the centre, and slightly 
impressed towards each extremity. 
Upper chalk, Kent and Wiltshire. 
Oreaster ocellatus. (Tab. XXI. fig. 13.) R. 4. 
Large irregular, nodose ossicles in the shape of depressed spheroids with 
truncated and finely radiated summits, and ocellato-punctated sides ; small im- 
pressed and angulated ossicula are interspersed. 
Evidently the fragments of a very distinct species of Oreaster. 
Upper chalk, Sussex and Kent. 
