320 MANUAL OF THE MOLLUSCA. 
gill, excretory opening behind it. Longitude 1, latitude 2 inches, 
2 species. 
PuysEemMA, A, Adams. 
Shell glassy, globular, contracted in the middle and drawn 
out to a point in front. 
Distribution, 1 species. "West coast of North America. 
Sormetus Adansonii, Bl., is described as semi-cylindrical, with sides grooved, nead 
indistinct ; shell unguiform, thin, and transparent. 
Atlas ( Peroni, Bl.), Lesueur. Head with two small tentacular lobes; body crn- 
tracted in the middle; foot dilated circularly, and fringed at the margin 
Famity III.—APLysIap@. 
Shell wanting, or rudimentary and covered by the mantle, 
oblong, trigonal, or slightly convoluted. 
Animal slug-like, with distinct head, 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. 
Type, A. depilans, Pl. XIV., Fig. 14. 
Synonym, Siphonotus (geographicus) Ad. 
Shell oblong, convex, flexible, and translucent, with a pos- 
terior slightly incurved apex. 
Ammal 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. 
Distribution, 42 species. West Indies, Norway, Britain, 
VWediterranean, Mauritius, China. 
The Sea-hares are mixed feeders, living chiefly on sea-weed, 
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. 
