COVERED-GILLED SUBGROUP 



3333 



ing shallow water in all parts of the world. In olden time there were many stories 

 in vogue respecting the poisonous nature of the sea hare, but it has been shown to 

 be harmless. It has the faculty of emitting a nauseous smell; and a beautiful 

 purple fluid is discharged from glands in the edge 'and inner surface of the mantle. 

 The species illustrated (A. depilans} occurs on the coasts of France and in the Med- 

 iterranean. It is reddish brown, with irregular and variable grayish blotches and 

 spots. It occurs in numbers on the Portuguese coast, and in stormy weather is 



SEA HARE, Aplysia (natural size). 



sometimes cast upon the shores in such quantities as to be the cause of epidemics, 

 and almost to render it worth while to extract the purple for economic purposes. 



Of another family (Oxynoidce} , we may take as an example Lobiger, which 

 includes elongate mollusks provided with a thin transparent shell, and having on 

 each side of the body two long parapodia, used as fins in swimming. The animal 

 has the power of casting off these lobes, and probably the posterior end of the 

 foot can also be spontaneously detached. Four species have been described from 

 the Mediterranean, Ceylon, Guadeloupe, and the Society islands. They are 

 separable on account of certain differences in the soft parts, but in a conchological 

 point of view they appear to be indistinguishable. In the family Pleurobranchidce , 

 the typical genus Pleurobranchus contains a 

 number of species from many parts of the 

 world, two of which occur on the British 

 coast. The one illustrated (P. peroni} is a 

 native of tropical seas, and was originally 

 obtained from the Mauritius. The body is 

 convex, ovate, with the mantle extending 

 over the back, and having a free margin at 

 the sides. Beneath this, on the right side, is 

 situated the large branchial plume. The 

 head is furnished with both labial and upper 

 tentacles, and at the inner base of the latter 

 are situated the eyes. A thin, membranous Pleurobranchus peroni (natural size) 



