426 
MOLLUSCA. 
Chitonellus striatus. — The Striated Chitonellus. 
Plate LXXXVII. tig. 10. 
Each valve with striae radiating from its apex; the margins 
serrated; the base of the last valve obtuse. Inhabits the seas 
of New Holland. 
Genus 27.—PHYLLIDIA— Lamarck. 
Generic Character. —Body creeping, oblorig-ovate, somewhat 
convex above; with a varicose, coriaceous, or tubercular skin, 
which forms a produced margin around the body; branchiae ar. 
ranged in a series of transverse leaflets under the margin of the 
skin ; four tentacula; organs of generation situated on the right 
side; anal orifice placed behind, on the back. Destitute of a 
shell. 
TRIBE VII.-TRITOXACEA. 
With exterior branchiae, placed over the mantle on the back 
or sides. Destitute of shells. 
Genus 28.—DORIS.— Linnceus. 
Generic Character .—Body creeping, oblong, sometimes plane, 
sometimes convex, and somewhat prism-shaped, bordered by a 
membrane which extends around from one side of the head to 
the other; mouth anterior, and placed below; four tentacula, 
two placed anteriorly on the body, in a concavity, the other two 
contiguous to the mouth ; anal orifice towards the base of the 
dorsal region, surmounted by fringed branchiae; orifice for genera¬ 
tion situated on the right side. 
Genus 29. —TE TH YS.— Gmelin. 
Generic Character .—Body fleshy, semi-pellucid, oblong, at¬ 
tenuated, and acute behind, with a broad semicircular mantle, 
which covers the head ; mouth anterior, and placed below; two 
tentacula; branchiae formed into branching tufts, naked, pro¬ 
jecting, and disposed in a double longitudinal series; anal open¬ 
ing and orifice for generation on the right side. 
Genus .30. — S C YLL J£* A. — Linnceus. 
Generic Character —Body creeping, gelatinous, oblong, late¬ 
rally compressed ; back raised into an elevated crest, and having 
