86 



Echinophora. — A stony polypifer, fixed, flat, or expanded 

 in a rounded membrane, free and bearing the form of a 

 leaf, finely striated on both sides. The upper surface is 

 echinulated with small papillae ; is besides supplied with 

 rose-formed, convex tubercles, considerably echinated, and 

 pierced with one or two holes, each covering a lamellated 

 star. 



The stars are scattered, circular, and covered ; the la- 

 mellae unequal, rather confused, projecting from the bottom 

 and sides, and partly filling up the cavity. 



Sp. 1. Echinoph. Rosularia. — Recent. Sea of New Holland. 



Explanaria. — A stony polypifer, fixed, expanded in a 

 free, foliaceous, undulated, or convoluted and sublobated 

 membrane, with one stelliferous surface. 



The stars scattered, sessile, and rather distinct. Recent. 



Explanaria differs from the following genus, astrea, in 

 its never, like the latter, heaping into a globular or hemi- 

 spherical mass ; but its expansions, at every age, preserving 

 their foliaceous form, and allowing their under surface to be 

 seen. The stars are only on the upper face ; are circum- 

 scribed, and not sunk in wrinkles or grooves. 



1. Expl. infundibulum. — Pall. Zooph. p. 332. 



2. — mesenterina. — Mad. Cinarescens. Sol. and Ellis, No. 26. 



Tab. xliii. 



3. — gemmacea. — Mad. Scabrosa ? Sol. and Ellis, p. 156. 



4. — aspera. — Mad. aspera. Sol. and Ellis, Tab. xxxix. 



5. — ringeus. — American Seas. 



6. — cristata. — Mad. Acerosa ? Sol. and Ellis, No. 30. 



Astrea — A stony polypifer, fixed, conglomerated, in- 

 crusting other bodies, or formed in a subglobose but rarely 

 lobated mass. 



The upper surface set with sessile, lamellated, round or 

 subangular stars. 



