422 
MOLLUSCA. 
of a roundish oval; the anterior margin shortest, and the pos¬ 
terior one large and rounded; the muscular impressions elon¬ 
gated, arcuated and transverse, situated under the posterior 
margin. 
Pileopsis Ungarica. — The Hungarian Pileopsis. 
Plate LXXXVII. fig. 31. 
Conical, vertex slightly spiral; longitudinally striated, and 
transversely wrinkled; covered with a fawn-coloured pilous 
epidermis; inside smooth, glossy, white, or rose-colour. Two 
inches in diameter. Inhabits the seas of Europe. 
Genus 18.—FISSURELLA.— Lamarck. 
Generic Character. —Animal with the head truncated in front; 
two conical tentacula, with eyes at their exterior base; mouth 
simple, terminal, and destitute of jaws ; two pectinated branchia? 
projecting from the cavity; mantle large, protruding beyond the 
shell. — Shell shield-shaped, conically depressed; concave with¬ 
in'; the vertex perforated; destitute of a spire; and of an ob¬ 
long-ovate shape. 
Fissurella Grceca. — The Greek Fissurella. 
Plate LXXXVIL fig. 20. 
Ovate-oblong, convex; the vertex with an ovate perforation ; 
stride cancellated, elevated, and the sections tuberculated; 
opening oblong-ovate, white or bluish ; outside yellowish-brown, 
sometimes clouded. Half an inch long. Inhabits the Euro¬ 
pean seas. 
Genus 19.—SIP HO.— Brown. 
Generic Character. —Animal unknown—Shell subcoriic, ver¬ 
tex turned to one side, slightly spiral, with a small fissure near 
the apex ; inside having a rhombic funnel-shaped syphon, corres¬ 
ponding with the external fissure ; ovate. 
Sipho striatus. — The Striated Sipho. 
Plate LXXXVII. fig. 21. 
White, with strong divergent striie and faintly striated con¬ 
centrically ; margin slightly crenulated ; the fissure triangular. 
Three-eighths of an inch long. Inhabits the sea at Greenock. 
