354 TORNATELLID-. 
and on rocks weeping. fresh. water. near the. sea-shore.. Both 
animal and shell are of a glaucous green color. 
Nona, Hz and A. Adams, - Shell white, fragile ;.outer lip pro- 
duced into awing behind. L, Algure (IXxxvil, Oi: 
ScapH: ANDER, Montfort. 
Biym. —Scaphe, boat, aner,man.. 
Distr.—13. sp. United States, Norway, Britain, Mediterra- 
nean on sandy ground, 50 fathoms. Fossil, 8 sp. Hocene—. 
S. lignarius, Linn. (1xxxvii, 23). ; 
Shell oblong, convolute; spirally striated ; aperture much 
expanded in frent; spire concealed; epidermis thick; lingual 
teeth 1°01, crested. 
Animal witha large oblong head, destitute of eyes ; foot short 
and broad ; lateral lobes reflected, but not enveloping the shell ; 
gizzard with two large trigonal plates and a small narrow trans- 
verse plate. It feeds on Dentalzum entale. 
AGLAIA, Renier, 
Syn.—Acera, Cuvier. Eidothea, Risso. Doridium,, Meckel. 
Distr.—3 ‘sp. ° South Europe. D. membranaceum,, Meck. 
Mediterranean. 
Animal oblong, truncated behind, the angles produced and 
dilated or filiform; head ovate-oblong, retuse in front; side-lobes 
expanded, wing-like : mantle investing a rudimentary, mem- 
branous shell. 
GASTROPTERON, Meckel. 
Distr.—G@. Meckelii, Bl. (lxxxvii, 24). Mediterranean. 
Animal oval, with sidelobes developed into wing-like expan- 
sions, meeting and uniting behind; cephalic disk triangular, 
obtuse in front, pointed behind, eyes centrally immersed ; lingual 
teeth 5°1°5; mantle (2), branchial plume exposed on the right side; 
reproductive orifice in front of the gill, excretory opening pond 
it. Shell almost microscopic. 
[ ATLAS, Lesueur. 
Referred to this family by several systematists, is a larval 
creature, and not of a mollusk —MAcDONALD. | 
‘Famiy TORNATELLIDA. 
aha geiiGnitts perfeetly retractile, but. iosoat of. dares size 
when expanded ; foot thick, reflexed on the sides; head broad, 
very often forming a flat disk, with or without other appendages ; 
tentacles broad, thick, united: at base ; ; eyes sessile near the base. 
Dentition, laterals numerous, unifor m, in diverging cross series, 
rachidian ‘teeth wanting (xiii, 68) ticiy 
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