CREl'IDULA. 271 



Crepidula fornicata. 



Fig. 17. 



Shell ovai, apex turned to one side, and terminating in the margin ; partition 

 appressed to one side. 



Patella fornicata, Lix. Syst. Nat. 12.'J7. — Martini, Conch, i. 160, t. 13, figs. 129, 130.— 

 Lister, Conch, t. 545, figs. 33, 35. — Knorr, Vergn. vi. t. 21, fig. 3. 



Crepidula fornicata, Lam. An. sans Vert. vii. 641. — Say, Journ. Acad. Nat. So. ii. 225 

 (July, 1822) ; ed. Binney, 73. — De Kay, N. Y. Moll. 157, pi. 7, figs. 1.52, 154.— 

 Stimpson, Cheek Lists, 4. 



Shell obliqiicly-oval, one side more oblique than the other, apex a 

 little prominent, turned to one side, not separate from the body of 

 the shell, and generally united with the margin 

 of the aperture ; convexity moderate, but vary- ^'^1^^ 



ing according to the object on which it is seated ; ^^^^^^ 

 surface wrinkled by the lines of growth, of a ^^B^r ^^R\ 

 dirty white color, and figured with interrupted, jH^^^^^ 

 waved, longitudinal lines, of a light chestnut col- H^M0^^| 

 or, and covered with a yellowish epidermis ; ap- ^^^H^^B 

 erture obliquely sub-oval, the edge entire and 1B|^^ M B| 

 sharp, color light brown, with darker dots and ^^^^^^ 

 blotches ; a ray from the apex along the middle c./omicata. 



of the shell generally lighter than the rest ; dia- 

 phragm white, occupying about one half the aperture, one side of it 

 defined by a distinct line, the other, for a consideral)le space, com- 

 pressed against the side of the shell, and firmly united to it, the free 

 edge waving, one half advancing considerably beyond the other, and 

 leaving a conspicuous notch at the side, outside the boundary line, 

 surface in general concave, but a narroAv, arched portion traverses 

 the middle. Length, one and one half inches ; breadth, one and 

 one fifth inches. 



Found adhering to other shells and to each other. 



This is probably, what Mr. Say supposed it to be, a variety of C. 

 fornicata, as originally described, and is a species found in various 

 seas. It is found occasionally thrown upon the beaches near Boston 

 after a storm, but is not uncommon about Cape Cod, and the islands 

 to the southeastward. The best specimens I have seen were brought 

 on oysters from Prince Edward's Island, off the mouth of the St. 

 Lawrence. Its shape varies according to the body on which it rests. 

 Four or five of different ages are frequently found riding upon each 

 other. When growing upon Peclen irradians it is found to have 



