Siluric Cysioidea and Cainarocrinus. — Schuchert. 233 
ment of the thecal plates. It is here made the type of a new 
genus, Coelocystis.' 
Emended definition. — Callocystinae with the theca varying 
between depressed echinus-shape with a deeply excavated base 
to elongate-globular form and with almost no excavated base. 
Theca with eighteen plates arranged as follows : 
Basal row has plates 4, 1, 2, 3. 
Second row has plates 5, 6 (sometimes part of 12), 7, 8, 9. 
Third row has plates 10, II, 12 (7, 8), 14. 
Fourth row has plates 16 (17 absent), 18, 13, (19 absent), 
15- 
Fifth row has deltoid 21 with madreporite and hydropore. 
Anal area not prominent, bounded by thecal plates 7, 8 and 
13. It is composed of two circles of plates, an outer of from 
10 to 14 pieces of very variable sizes, and the pyramid with 
6 or 8 pieces. 
One basal and two upper discreet pectinirhombs with nu- 
merous dichopores. 
Ambulacra not much elevated above and but slightly exca- 
vated into the theca, beginning with four rays and bifurcating 
variously in different specimens of the same species until 27 
branchlets result. Brachioles widely separated, slender, short 
and club-shaped. 
Madreporite large, with a small hydropore immediately be- 
neath. The latter is closed by a pyramid of 4 or 5 pieces. 
Column stout, tapering rapidly for a short distance and then 
hardly at all throughout its length. Total length about 95 mm. 
Base of attachment terminating in a few roots. 
Genotype, 5". mitltifasciatiis Hall. 
Sphaerocystites globularis n. sp. 
Length of a large and regular theca 22 mm., transverse di- 
ameter 20 to 21 mm. Base not excavated. Plate 12 resting on 
plate 6 of the second circle. 
Ambulacra branching with no apparent regularity, the 
branches in adults varying between 9 and 14. Ambulacralia 
about 7 to one parambulacralium. 
Anal pyramid depressed, composed of 8 pieces and sur- 
rounded by a ring of 4 large and 10 small plates. 
Hydropore minute closed by a pyramid of 5 pieces and sit- 
uated immediately in front of the elongate dumbell shaped 
madreporite on plate 21. 
