192 MALACOZOA. GASTEROPODA. NUDIBRANCHIATA. 



The animals of this order, all marine, have a consi- 

 derable resemblance to Slugs, and crawl much in the 

 same manner as they. 



SECTION I.— POLYBRANCHIATA. 



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

 papillce, disposed along the sides of the body above. 



Family I. — iEoumNA. 



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. iEous. 



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 papUlosa. 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 

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

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

 brownish-black. Length about two inches. 



