102 GASTEROPODA. 



Genus 22. — UMBRELLA.— /.ama/c/;. 



Generic Character. — Body of the animal very thick, some- 

 what oval, and provided with a dorsal shell ; foot large, smooth, 

 and flat underneath, surrounded by a border, anteriorly notched, 

 attenuated behind; head indistinct; four tentacula, the two 

 upper ones thick, short, and truncated, the other two thin, and 

 shaped like pedunculated crests ; having foliaceous branchiae. — 

 Shell external, orbicular and somewhat irregular ; slightly con- 

 vex above, with the vertex towards the centre ; internal cavity 

 but slightly hollowed ; lips smooth. 



Umbrella Indica. — The Indian Umbrella. Plate XIV. 

 fig. 24'. Ovate, slightly convex above •, the vertex towards the 

 centre ; whitish, summit yellow, longitudinally striated, and con- 

 centrically wrinkled ; inside with radiating striae. Four inches 

 in diameter. Inhabits the Indian seas. 



GewMs 23.— PLEUROBRANCH US.— ZawmrcA. 



Generic Character. — Body creeping, fleshy; mantle and foot 

 expanded ; branchiae placed on the right side ; cloak enveloping 

 the shell ; neck short, contracted in some species, with an emar- 

 ginate front, exhibiting the commencement of the inferior ten- 

 tacula, the upper ones tubular and cloven ; gills at the edge of 

 the dorsal plait, in front of which are the generative and anal 



orifices ; mouth provided with a short retractile proboscis Shell 



dorsal and internal, thin, flat, and obliquely oval. 



Pleurohranchus plumula. — The Plumed Pleuroeranchus 

 Plate XIV. fig. 14. Ovate-oblong, depressed, pellucid, yellow- 

 ish-white, concentrically wrinkled, almost entirely open, rounded 

 and convoluted ; the vertex with a single turn. Kalf an inch 

 long. Inhabits the Devonshire coast. 



TRIBE VI. PHYLLIDIACEA. 



The branchiae are situated beneath the margin of the niantle 

 in the longitudinal series around the body. Animals respiring 

 in water. 



