836 CRETACEOUS ECHINODERMATA. 
for the reception of pedicellariz. Ossicles of disc polygonal, those opposite the 
arms arranged in rows, the central row longest, and eventually forming broad 
plates on the surface towards the terminations of the arms. Many of them, 
especially below, marked with grooves for the pedicellariz. 
In the collection of the Marquis of Northampton, and in the British Museum. 
The Asterias Schultzii of Roemer, from the Quader-sandstein of North Ger- 
many, appears to be this species. 
Stellaster elegans. (Tab. XXII. fig. 9.) R. 4. 
Disc narrow in proportion to the arms, which are long and slowly tapering. 
Marginal plates of upper surface centrally narrow widening upon the arms, and 
becoming nearly square, rounded at sides. Ossicles of disc forming three ra- 
diating rows opposite the arms and becoming rapidly transformed on the latter 
into square plates. No traces of pedicellariz. 
Differs from the last in proportions, and in the smoothness of its plates, which 
present no grooves for the reception of pedicellariz. 
In Mr. Bowerbank’s collection. 
Greensand of Blackdown ; also in the Greensand (upper) at Folkstone, where 
it was observed by Capt. Ibbetson and myself. 
ARTHRASTER (ap0poy a joint, astnp a star), Forbes. 
One of the most beautiful and singular of cretaceous star-fishes is that figured 
in Tab. XXIII. fig. 1. It is quite new generically and specifically, and closely 
allied to the living genus Ophidiaster, but the ossicula of the arms are very com- 
pactly articulated together, and much fewer in number. ‘Their arrangement is 
also very different: exclusive of the ambulacral ossicula, which are unknown, 
only seven bones enter into the composition of the framework of the arm trans- 
versely, and these alternate in such a manner as to form a compact skeleton 
without conspicuous interstices. All the seven ossicles are similar in form, each 
consisting of a transversely oblong expanded though linear base, terminating at . 
each end in an acute angle, and bearing along the centre a linear crest or ridge 
with steep sides ; the central one is largest. I propose to name this beautiful 
species Arthraster Dixoni. The only known specimen consists of the remains 
of six or seven long and rounded arms, each of which, when perfect, probably 
measured nearly 8 inches. It is from the lower chalk of Balcombe pit, near 
Amberley, Sussex. 
