CONCHIFERA. 
m) 
Cleodora pyramidata. — The Pyramidal Cleodora. 
Plate LXXXVII. fig. 9. 
Pyramidal, triangular; of a gelatinous or cartilaginous sub¬ 
stance, very thin and transparent; aperture obliquely truncated. 
Inhabits the American seas. 
Genus 5. — CLIO.— Lamarck. 
Generic Character. —Body naked, gelatinous, oblong, turbi¬ 
nated, swimming; head projecting, surmounted by numerous 
retractile tentacula, disposed in two fasciculi; two eyes placed 
above; mouth terminal; two opposite branchial fins, situated at 
the base of the neck; anal and generative orifices, placed on the 
right side, near the neck, and under the fin. Destitute of a 
shell. 
Genus 6—HYALiEA — Lamarck. 
Generic Character. —Body enclosed in a shell, winged before; 
two opposite wings, somewhat retractile, inserted at the sides of 
the mouth; head indistinct; mouth terminal, placed at the junc¬ 
tion of the fins; without eyes; branchiae lateral; shell horny, 
transparent, oval-globular, with three teeth behind, open at the 
summit and the two posterior sides. 
Hyalcea tridentata — The Three-Toothed PIyalasa. 
Plate LXXXVII. fig. 12. 
Transparent, horn-coloured, globular; posteriorly tridentate ; 
summit and two posterior sides open; yery finely striated trans¬ 
versely. Three-fourths of an inch long. Inhabits the Medi¬ 
terranean. 
CLASS II.—CONCHIFERA. 
Animals soft with articulations, destitute of head or organs 
of vision, and always fixed within a bivalve shell ; having exter¬ 
nal branchiae; a simple circulation, and a unilocular heart. 
All the shells of this class live in the sea or in fresh water. 
None of the animals have an internal shell. The body is inva- 
