192 MALACOZOA, GASTEROPODA. NUDIBRANCHIA-Ei, 



The animals of this order, all marine, have a 

 derable resemblance to Slugs, and crawl much in the 

 same manner as they. 



SECTION I. POLYBRANCHIATA. 



Branchia numerous, in the form of arbuscules, lamina, or 

 papilla v disposed along the sides of the body above. 



FAMILY I. JEoLiDiNA. 



Body oval, oblong, or elongated, limaciform, with the 

 skin smooth ; the branchiae in the form of shreds, cirri, 

 or papillae, disposed along the sides ; two pairs of tenta- 

 cula, the one occipital, the other frontal ; the eyes 

 placed behind the latter. 



GENUS 1. ^EoLis. 



Body oblong, tapering to a'point behind, convex above, 

 flat beneath ; head short, with four tentacula, two upper 

 and two labial ; eyes two, placed at the base of the upper 

 tentacula ; branchiae of numerous soft filaments or 

 laminae, disposed in rows along the sides of the back ; 

 genital and alimentary organs terminating on the right 

 side. 



1 . JEolis papill6sa. Papillate JEolis. 



Body linear-oblong, tapering behind to an obtuse point, 

 convex above, flattened beneath, laterally compressed ; the 

 head with four tentacula, the upper conical, obtuse ; the back 

 smooth, its sides with numerous soft, subulate, branchial fila- 

 ments, extending their whole length, those nearest the foot 

 shorter ; the mouth with a thick circular margin, an internal 

 very thin circular lip, and opening by a vertical slit, bounded 

 by two thin horny plates, of which the tip is pointed; foot 

 oblong, anteriorly abrupt, with the angles pointed, obtuse be- 

 hind ; the colour dusky, tinged with purple, the branchiae 

 brownish-black. Length about two inches. 



