PLEUROBRANCHUS. APLYSIA. 



80. PLEUROBRANCHUS. 



are composed of leaflets, 



more or less divided, at- 

 tached along the right side 



(fig. 80, br), or on the 



back (fig. 81), and more 



or less covered by the 



mantle, which almost al- 



ways encloses a small 



shell in its thickness. 



Their form is very variable. They are divided into Pleurobran- 



chus, Pleurobranchides, Aplysia, Dolabella, Akera^ &c. 



37. The PLEUROBRANCHI are mol- 

 lusks of an oval form ; in which the 

 branchice are fixed on the right side, 

 between the mantle and foot (fig. 80). 

 V The mouth is in the form of a proboscis 

 or trunk, and is surmounted by a small 

 triangular veil, and two tentacles; they 

 have four stomachs, the second one of 

 which is sometimes armed with bony 

 pieces, and the anus opens behind the 

 branchioe. One species, of a lemon 

 yellow colour, is found on the coasts of 

 m France. 



j, 38. The APLYSIJE, which the ancients 

 called sea-hares, have a very singular 

 form ; the body resembles that of a 

 sort of Limax ; but the edges of the 

 foot, erected in flexible crests, surround 

 the back and may be even reflected over 

 it. Their head is supported by a neck 

 of greater or less length, and furnished 

 with four tentacles (fig. 81, ?)> the two 

 upper ones being hollowed like the ears 

 of a quadruped, and placed above the 



eyes (y). The branchia?, in the form of very complicated 



Fig. 81. APLYSIA 



Explanation of Pis. 8'\ m. the mantle, raised up to show the branchiae, 

 &r / a. the anus ; 6. the mouth and trunk ; . the veil ; t. the tentacles ; 

 p. the foot 



Explanation of Fig. 81. /, t. the tentacles ; y. the eyes ; m. the mantle ; 

 6. the hranchire. 



37. What are tb-3 characters of the genns Pleu'robranchus ? (Pleuro- 

 branchus, from the Greek, pleura, side, and brfigchia, gills.) 



38. What are the characters of the genus Ap.y'sii? (Aplysia, Iron* 

 the Greek, nplvsia, uncleanness.) 



