116 GASTEROPODA. 



long. Inhabits the British seas, as well as those of other 

 parts of Europe. 



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, which are somewhat 

 pedunculated ; mouth below, funnel-shaped, oblique, trun- 

 cated, 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 minute, pointed, 

 inclined backwards. 



Parmophorus Australis The Australian Parmo- 



PHORUS. Plate XIV. fig. 22. Shell oblong, depressed ; 

 vertex slightly recurved; concentrically striated; the pos- 

 terior margin rounded, and the anterior truncated. Two 

 inches long. Inhabits the Australian coasts. 



TRIBE V. SEMIPHYLLIDIA. 



Branchiae situated under the margin of the mantle, and 

 set in a longitudinal series, on the right side of the body. 

 The animals respire water. 



Genus 22— UMBRELLA Lamarck. 



Generic Character. — Body of the animal very thick, 

 somewhat oval, and provided with a dorsal shell ; foot very 

 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; 

 foliaceous branchiae, between the foot and the slight margin 

 of the mantle, along the right side. Shell external, orbicu- 



