160 



POPULAR CONCHOLOGY. 



the gills lie on the left side, far towards the back; the 

 foot is divided behind by an oblique notch, and ends in 

 lobes which cover the gills. — 1 species. 



Poster obranchaa maculata was found by D'Orbigny on 

 the coast of Chili. 



Family 2. — APL YSIA CEA. 



The gills are situated on the back of the animal, and 

 are either covered by a shield, or a rudimental shell ; the 

 tentacula are distinct. — Marine. 



Aplysia. Lin, — Shell, or operculum for the gills, an 

 oval, generally thin, nearly transparent plate, 

 with only rudimentary indications of a spire. 

 Animal ovate, convex; its head pedicled, 

 furnished with four auriculated tentacula ; 

 at the anterior and lateral bases of the 

 upper two are the small sessile eyes; shell 

 imbedded in an opercular lobe, placed cen- 

 trally in the back, and protecting the bran- 

 chial plume, which is not protruded; mantle with large 

 lateral lobes folding over each other, and protecting the 

 operculum, but capable of being used for swimming ; foot 

 oblong; mouth subproboscidiform, armed with corneous 

 jaws ; tongue armed with a single row of hamated central 

 teeth, and numerous uncinated laterals ; gizzard studded 

 with cartilaginous plates.* — Many species. 



These animals resemble large slugs ; they swim easily, 

 but crawl slowly: they are found in the Mediterranean 

 Sea. Darwin, in his Journal f, says it feeds on delicate 



* Forbes' s British Moll. 



•j- Journal of Researches into the Geology and Natural History of 

 the Countries visited by the Beagle. 



