6 



RANDOM NOTES ON NATURAL HISTORY. 



The Shell-Bearing Mollusca of Rhode 

 Island. 



BY HORACE F. CARPENTER. 



Chapter XII. 

 Family 22. Calyptrseidoe, Gray, con- 

 taining twelve genera and more tlian one 

 hundred species, is represented in Rhode 

 Island by five species, as below. The Calj-p- 

 trseidae, or Slipper limpets, are found ad- 

 hering to rocks, or under stones, on both 

 living and dead shells of other species, and 

 to each other, from lovr water to forty 

 fathoms. They are numerous and widely 

 difiused, but reach their perfection in the 

 tropics, where they attain considerable size 

 and are remarkable for their peculiar forms 

 and the richness of their colors. Like the 

 oyster, when first born they are free to 

 move about and select a place to settle, 

 from which spot they never move again. 

 They adapt the form of their growing shells 

 to the inequalities of the surface on which 

 they ma}^ be fastened. 



Genus Crucibulum, Schum., 1817. 



Shell sub-conical ; aperture wide, with a 

 cup-shaped appendage within, attached on 

 one side to the inner wall of the shell. 



Sub-genus Dispot^a, Sat. (Calypeopsis, 

 Lesson.) 



24. Crucibulum (Dispot^a) striata. Say. 



Syns. : 



Calyptrsea striata, Say, J. Ac. Nat. Sc, 

 Phila., v., 216, 1836. 



Crucibulum striata, IT. & A. Adams, 

 Genera, i., 366, 1858. 



Shell oval, convex, covered with numer- 

 ous equidistant, radiating lines; apex sub- 

 acute, wax-yellow in color, turned a little 

 to the left side and to the posterior end. It 

 has a cup-like process within, attached by 

 one side to the shorter side of the shell. 

 Length four-fifths of an inch. Distribu- 

 tion, from New Jersey to the Bay of Fundy. 

 (Verrill and Smith.) Northern N. J. (Say.) 

 Gardiner's Bay and Montauk Point. (S. 

 Smith.) Vineyard Sound and Buzzard's 

 Bay, 3 to 12 fathoms. (A. E. Verrill.) 

 Mount Desert, Me., 3 to 10 fathoms, com- 

 mon, and Ba}' of Fundy, low water to 30 

 fathoms, common. (A. E. V.) Whole 



coast of New England. (Stimpson.) I 

 have never found it in R. I. 



Genus Crepidula, Lam., 1799. 

 Shell oval, arched, boat shaped, ^with a 

 spiral apex pressed against the margin ; in- 

 terior with a horizontal partition covering 

 its posterior half. 



25. Crepidula convexa. Say. 

 Syns. : 



Crepidula glauca, var, Say, J. Ac. Nat. 

 Sc, Phila., II., 226, 1822. 



Crepidula acuta, H. C. Lea, Am. J. Sc, 

 xlii., 108, 1842. 



Crepidula convexa. Say, J. Ac Nat. Sc, 

 Phila., II., 227, 1822. 



Shell very convex, the var glauca not so 

 much so, color from greyish-green to dark 

 brown; apex acute, separated from the 

 body of the shell ; within, shining, dark 

 brown ; aperture oval with a diaphragm 

 across, occupying less than half the inte- 

 rior, leaving a deep cavity extending to the 

 beak ; diaphragm brown, the free edge 

 white. Length half an inch, breadth a little 

 less. Distribution, Massachusetts Bay to 

 Florida, common ; less abundant and local 

 to Gulf of St. Lawrence. Very abundant in 

 Rhode Island on stones and on small uni- 

 valve shells, such as Ilj'anassa obsoleta, etc. 

 The var glauca is found on broad and flat 

 surfaces of stones, and larger bivalve 

 shells. My a. Pecten & Ostrsea. 



Gould says {Invert. 3fass., 273, 1870.) it 

 is found on sea-weed, but I have never 

 found it so, excepting a few very srnall, 

 young specimens. 



2G. Crepidula fornicata, Linn. 

 Syns. : 



Patella fornicata, Linn., Mart., Lister, 

 Knorr. 



Crepidula fornicata. Lam., Sa}', DeKa}', 

 Stimp., Gould. 



Shell oval, but with one side more ob- 

 lique than the other; apex prominent, 

 turned a little to one side, not separate 

 from the margin, externally dingy white, 

 figured with chestnut-colored lines, and the 

 whole surface covered with a yellowish epi- 

 dermis ; aperture sub-oval, the edge simj)le 

 and entire, color light brown ; diaphragm 

 white, occupying one-half the aperture, one 

 side appressed to one side of the shell, the 

 other defined b}' a distinct line, the free 



