250 Mr. F. M‘Coy on some new Paleozoic Echinodermata. 
verse suture between the first and second series of supra-basal 
plates nearly medial; base flattened; surface minutely gra- 
nulated.. Length 3 lines, width 3 lines. | 
If we suppose the lower third abruptly cut off a P. ellipticus, 
we should have a good idea of this little species, which agreeing 
with the above in most characters is distinguished by its small 
size, more tapering ambulacra, greater proportional width and 
wide base. 
Rare in the carboniferous limestone of Derbyshire. 
(Col. University of Cambridge.) 
Codaster (M‘Coy), n. g. 
Etym. coder, tintinnabulum, and aornp, stella. 
Gen. Char. Cup conical, with the upper part broad, flat, trun- 
cate ; pelvis deep, conical, of three pieces, one tetragonal and 
two pentagonal, each having its imner apex 
notched to form part of the round columnar 
canal; on the upper edges of these rest five 
large equal first supra-basal plates which reach 
to the truncated summit, to which from their 
mesial gibbosity they give a pentagonal out- 
line ; in the centre of this superior disc the pat terminal disc 
mouth seems situated, and from it five promi- of Codaster. 
nent, minutely porous pseudambulacra diverge, 
one to each angle, each being placed on a thick tapering ridge 
divided by a mesial sulcus ; from the re-entering angles of those 
ridges four other thick, rapidly tapering ridges proceed, one 
to the middle of each of four of the straight sides, each ridge 
at its thick, oral end shows an obscure impression, probably 
of the ovarian pores ; the fifth space is without a ridge, being 
occupied by a large, ovate or lozenge-shaped (? anal) opening ; 
the depressed, triangular intervening spaces are marked with 
coarse, rough parallel striz nearly coinciding in direction with 
the pseudambulacral ridges, and converging to the second set 
of ridges ; the impressed lines between these strize seem punc- 
tured, the fifth (? posterior) space is without sulcation, 
These strange and beautiful forms, the ‘hell-stars, as they 
may be called, are obviously allied to Pentremites (taking P. Der- 
biensis, florealis, oblongus, ellipticus, and such like as the types of 
the genus), from which they differ in having the small basal 
plates enormously developed into a conical pelvis, and having the 
pseudambulacra entirely confined to the capital plates (which here 
found by MM. Roemer and Yondell (Bulletin de la Soc. Géol. de France 
for 17th April 1848) to be really the alimentary canals of a double row of 
little jointed tentacles resembling I imagine-those of Pseudocrinites. 
