102 GASTEROPODA. 



Genus 22. — UMBRELLA.— Lamarck. 



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 branchite. — 

 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 wath radiating strise. Four inches 

 in diameter. Inhabits the Indian seas. 



Genus 23.— PLEUROBRANCH US.— Zamarc)^. 



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

 expanded ; branchiae placed on the right side ; cloak enveloping 

 the shell j 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 wdth a short retractile proboscis. — Shell 

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



Pleurohranchus plumula. — The Plumed Pleurobranchus 



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. Half an inch 



\ long. Inhabits the Devonshire coast. 



TRIBE VI. PHYLLIDIACEA. 



The branchiae are situated beneath the margin of the mantle 

 in the longitudinal series around the body. Animals respiring 

 in water. 



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i^„_. 



