188 AMERICAN MARINE CONCHOLOGY 
The figure is a copy of the original. I have not been able to 
identify this species. 
Genus LITHODOMUS, Cuvier. 
Reg. Anim., ii. 461. 1817. 
The animal, which is eaten in the Mediterranean, is like a com- 
mon mussel; but differs in habit, boring into corals, shells, and 
the hardest limestone rocks; its burrows are shaped like the shell, 
and do not admit of free rotatory motion. The genus inhabits 
warm seas, ; 
1. L. rorrrcatus, Ravenel. 
Proc. Philad. Acad., 44. 1861. 
Shell thin, fragile, white ; posterior end with a narrow projec- 
tion on each valve, deflected so as to cross each other; within 
light salmon color. 
Length 31 mill. 
Charleston, S. C. 
From a mass of coral drawn up by a fishing line, in 14 fathoms 
off Charleston Bar. There was quite a colony of these shells in 
the coral. Possibly ballast from some distant locality? <A 
similar species inhabits the Caribbean Sea. 
7 
Genus CRENELLA, Brown. 
Hist. Brit. Conch. 1827. 
There are about 25 species of this genus, inhabiting temperate 
and arctic seas. Low water to 40 fathoms. Spinning a nest, or 
hiding amongst the roots of sea-weed and corallines. 
a. Typical species. Surface of valves entirely covered by striae, 
radiating in two diverging fasciculi from the beaks. Shell sub- 
orbicular or oval. 
1. C. GLANDULA, Totten. Fig. 515. 
(Modiola.) Am. Journ. Sci., xxvi. 367, f. 3, e. f. g. 
Mytilus decussatus, Stimpson, Shells N. E., ii. 1851. 
Shell oblique, oval, orbicular, inflated, thin, radiating lines 
crowded; inner margin crenulated; epidermis brownish-yellow ; 
within pearly. 
Length 12, breadth 9 mill. 
New England, northwards. 
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