12 
TRIBE I. ASTRJ5ACEA. 
Plate 5, fig. 40, animal natural size ; a, one of the tentacles ; h, a transverse 
section of the same. 41. The animal as it occurs half-concealed in the sand, 
— San Lorenzo, Callao, Peru. — Eip. Exp. 
Metridium mdscosum {Drayton). — Much depressed, an inch high, and 
inches in diameter; sides furnished with suctorial vesicles; disk faintly ra- 
diated, scarcely plicate at the margin ; tentacles subulate, in three series, 
nearly f of an inch long, stout, and scattered among them are numerous fron- 
descent appendages, not over three lines in length. 
Plate 5, fig. 42, the expanded animal of natural size; 43, the same, as it 
lies embedded in the sand. — From sandy pools among the rocks, left by the 
tide, Wollongong, Illawarra, New South Wales. — Exp. Exp. 
Family II.— ASTRiEIDiE. 
Animals with numerous tentacles arranged along the margin 
of the disks, and covered by the same on contraction. The 
disks either simple, or budding in lines and long-confluent. Co- 
ralla calcareous, with concave radiate cells ; larnellge, in aggre- 
gate species, not continuous from one centre to another, but 
generally interrupted half-way; the stars, therefore, circum- 
scribed. 
The genera of Astrasidse may be arranged and characterized 
from the coralla as follows : 
I. LamellcB of the cells large, and entire or nearly so ; coralla calicularly 
branched, or stipitate [explanato- glomerate). 
Genus I. Euphyllia. Coralla calicularly branched, calicles subturbinate, 
lamellae thin, bottom of the cell very narrow and often concealed by the large 
lamellae. 
Genus II. Ctenophyllia. Coralla explanato-glomerate, meandrine; la- 
mellae very stout and remote. 
II. Lamellce of the cells dentate or denticulate, rarely entire and then minute ; 
coralla calicularly branched or glomerate, the septa rarely foliaceous. 
Genus III. Mussa. Calicularly branched or explanato-glomerate ; calicles 
subturbinate, cells large and concave, sometimes meandrine ; lamellae coarse 
and dentate, very unequal and unequally exsert (6 or 7 in a breadth of a fourth 
of an inch, and half of these smaller). 
