138 



2. C. alius. — Subovate ; vertex conoidal, considerably 

 vaulted ; areas granulated, the larger without, the smaller 

 within, the petaloidal spaces formed by the ambulacra. 



This species is only known in a petrified state. It is 

 distinguishable by its size, being, sometimes, six inches 

 long, and two inches in height, by its rising in a round 

 vaulted form; and. by its ambulacra being large and wide. 

 Fossil. 



The casts of the two last species form very interesting 

 fossils. — Organic Remains, PI. ii. fig. 8, and PI. iv. fig. 7. 



3. C. ovatus. — Ovate ; the margin not waving, the upper 

 part convex, with four pores in the vertex ; the ambulacra, 

 in petaloidal forms, not united at their lower terminations, 

 but the one side of each ray extending farther than the 

 other; the surface covered with minute tubercles; the base 

 flat ; the mouth subreniform, with five prominent lips, from 

 the hollowed spaces between which proceed five grooves ; 

 the vent in the margin. Recent and fossil, — Leske ap. 

 Klein. Tab. xx. fig. c. d. 



4. C. orbiculatus. — This is a fossil which was placed, 

 by Leske, under this genus, with considerable doubt, it 

 being so injured that the state of the under part could not 

 be ascertained. 



5. C. marginatus. — With a convex stelliferous vertex ; 

 with short ovato-acute ambulacra ; the margin rather thin, 

 expanded, and broad. Fossil. — Scilla, Corp. mar. Tab. xi. 

 fig. inferior. 



6. C. scutiformis. — Elliptical ; the back flattish and sub- 

 marginated. — Seba, mus. iii. Tab. xiii. fig. 23, 24. Encyc. 

 PI. cxlvi. fig. 1, 2. 



7. C. laganum. 



EchiriocUscus laganum. — Leske ap. Klein, Tab. xxii. 

 fig. a. b. c. 



8. C. excentricus. — Suborbicular, depressed, but rather 

 convex ; five narrow ambulacral compartments divaricating 



