320 MANUAL OP THE MOLLTJSCA. 



gill, excretory opening beLind it. Longitude 1, latitude 2 inclies, 

 2 species. 



Physema, a. Adams. 



Shell glassy, globular, contracted in tlie middle and drawn 

 out to a point in front. 



Distrihution, 1 species. "West coast of North America. 



Sormetus Adansonii,'B\., is described as semi-cylindrical, with sides grooved, nea*l 

 indistinct ; shell unguiform, thin, and transparent. 



Atlas (Per onii, B].), Lesueur. Head with two small tentacular lobes; body con- 

 tracted in the middle ; foot dilated circularly, and fringed at the margin 



Family III. — Aplysiad^. 



Shell wanting, or rudimentary and covered by tbe mantle, 

 oblong, trigonal, or slightly convoluted. 



Animal slug-like, with distinct bead, tentacles, and eyes; 

 foot long, drawn out into a tail behind ; sides with extensive 

 lobes, reflected over the back and shell ; branchial plume con- 

 cealed. Sexes united. 



Aplysia, Gmelin. Sea Hare. 



Ty2Je, A. depilans, PI. XIV., Fig. 14. 



Synonym, Siphonotus (geographicus) Ad. 



Shell oblong, convex, flexible, and translucent, with a pos- 

 terior slightly incurved apex. 



Animal oval, with a long neck and prominent back ; head 

 with four tentacles, dorsal pair ear-like with eyes at anterior 

 lateral bases ; mouth proboscidiform, with horny jaws, lingual 

 teeth 13.1.13, hooked and serrated, about 30 rows; gizzard 

 armed with horny spines ; sides with ample lobes folding over 

 the back, and capable of being used for swimming ; gill in the 

 middle of the back, covered by the shell and by a lobe of the 

 mantle, which is folded posteriorly to form an excretory siphon. 



JDistrihution, 42 species. West Indies, Norway, Britain, 

 Mediterranean, Mauritius, China. 



The Sea-hares are mixed feeders, living chiefly on sea-woed, 

 but also devouring animal substances; they inhabit the 

 laminarian zone, and oviposit amongst the weed in spring, at 

 which time they are frequently gregarious. (Forbes.) They 

 are perfectly harmless animals, and may be handled with 

 impunity. When molested they discharge a violet fluid from 

 the edge of the internal surface of the mantle, which does not 

 injure the skin, has but a faint smell, and changes to wine-red. 



