MOLLUSCA. 
423 
Genus 20. — EMARGINULA.— Lamarck. 
Generic Character. —Body ot the animal creeping; having 
two conical tentacula, with the eyes placed at their external 
base; mantle large, partly covering the margin of the shell; 
foot large and thick.—Shell conical, shield-shaped; vertex in¬ 
clined to one side; internal cavity simple; the dorsal margin 
with a fissure. 
Emarginula fissura. — The Slit Emarginula. 
Plate LXXXVII. fig. 17. 
Oval, with reticulated striae, and ribs radiating from the ver¬ 
tex, which is obtuse and slightly recurved; margin with a 
fissure, which extends nearly half way to the vertex; inside 
glossy white. Three-eighths of an inch long. Inhabits the 
British seas. 
Genus 21.—PARMOPHORUS. — Lamarck. 
Generic Character. —Body creeping, very thick, oblong-ovate, 
broad behind, obtuse at the extremities ; border of the mantle 
cleft before, and suspended vertically around; back shell shield¬ 
shaped, and partly covered ; head distinct, and slit below ; two 
conical contracted tentacula, at the base of which are placed 
the eyes, and are somewhat pedunculated; mouth below, 
funnel-shaped, oblique, truncated and concealed; branchial 
cavity opening anteriorly behind the head by a transverse fissure. 
—Shell oblong, somewhat in the form of a parallelopiped ; 
slightly convex above, with a small sinus before; apex pointed, 
inclined backwards. 
Parmophorus Australis. — The Australian Parmophorus. 
Plate LXXXVII. fig. 22 . 
Shell oblong, depressed; vertex slightly recurved ; concen¬ 
trically striated •, the posterior margin rounded, and the anterior 
truncated. Two inches long. Inhabits the Australian coasts. 
TRIBE V.-SEMIPHYLLIDIACEA. 
Branchiae situated under the margin of the mantle, and set 
in a longitudinal series, on the right side of the body. The 
animals respire under water. 
2 m 2 
