92 AMERICAN MARINE CONCHOLOGY. 
nate; apex with an indented transverse line at the larger end of 
the perforation. 
Height 10, length 20, diam. 15 mill. 
Southern Coast. 
Genus CEMORIA, Leach. 
Lowe, Zool. Journ., iii. 76. 1826. 
Rimula, Lovén (not Defrance), Ind. Moll. Scand. 21. 1846. 
Puncturella, Lowe, Zool. Journ. iii. 78. 1827. 
In the second edition of Gould’s Invertebrata of Massachusetts, 
occurs an error in the description of this genus which it is neces- 
sary to correct: the apex is said to be “curved forwards, with a 
fissure just behind the apex.” This is reversing the real position, 
as the apex is recurved, with the fissure in front. See the illus- 
tration of shell, with animal, in H. and A. Adams’ “ Genera,” t. 
Dive AT. . 
1. C. Noacuina, Linneus. Figs. 184, 185. 
(Patella.) Mantissa, 551. 1771. 
Patella aperta, Montagu, Test. Brit. 491, t. 138, £10. 1803. 
Patella fisswrella, Miller, Zool. Dan. i., t. 24, f. 4-6. 1788. 
Cemoria Flemingti, Leach, Sowerby, Conch. Man., f. 244. 1842. 
Sipho striata, Brown, Brit. Conch. t. 36, f. 14-16. 1844. 
Cemoria princeps, Mighels and Adams, Bost. Journ. iv. 42,t. 4,f.3. 1842. 
Diodora Noachina, Stimpson, Shells, N. E. 30. 1851. 
Shell small, conical; apex recurved, obliquely perforated ; sur- 
face covered by about twenty unequal radiating ribs which feebly 
crenate the margin. 
Height 2.5, length 5 mill. 
NV. of Cape Cod, Masa. (N. Hur.) 
Family CALYPTRAID A. 
Shell limpet-like, with a more or less spiral apex; interior (in 
our species) divided by a shelly partition to which the adductor 
muscles are attached. 
The animal has a lengthened muzzle; eyes on the external bases 
of the tentacles; branchial plume single. They feed on sea-weed, 
and live attached to the surface of rocks or other shells, their 
forms modified to conform to the situation they inhabit. 
Synopsis of Genera. 
Shell subconic, spiral ; apex subcentral ; aperture wide, with the internal 
appendage entire and cup-shaped, attached by one of its sides. 
CrucrsuLuM, Schum. 
