164 FISSURELLA. 



Patella nimbosa Linn. Syst. Nat. x, p. 785. — F. nimbosa Lam. 

 An. s. Vert, vi, 2d pt., p. 10. — Eeeve Conch. Icon. f. 29. — Sowb. 

 Thes. Conch, p. 192, f. 136. 



Has more the aspect of the Chiliau species than of the West In- 

 dian. It is a dark shell, obsoletely ribbed and rayed with black. 



F. nodosa Born. PI. 37, figs. 46, 47, 48. 



Shell conical, elevated, the base oval. Apex a little in front of 

 the middle. Sculptured with strong nodose radiating ribs. Orifice 

 oblong, more than twice as long as wide, contracted in the middle, 

 one-seventh to one-ninth the length of shell. 



The form is variable but usually much elevated. Unicolored, 

 varying from brown to white. Ribs prominent, principal ones about 

 23 in number, but usually there ai'e some small interstitial riblets 

 also. These ribs are conspicuously nodose. Inside white ; margin 

 conspicuously dentate. 



Length 36, breadth 25, alt. 17 mill. 



Length 29, breadth 22, alt. 15 mill. 



Tortugas ; Florida Keys ; Bermuda ; West Indies generally south 

 to Barbados. 



Patella nodosa Born, Test. Mus. Cebs. Vindob. p. 429, 1780. — 

 Fissurella nodosa of Lamarck, Reeve et al., and of Arango, Fauna 

 Mai. Cubana, p. 228.— Dall Prelim. Cat. Moll. S-E. U. S., p. 170. 

 — Patella spinosa Gmel. Syst. Nat. xiii, p. 3731. — Patella Jamai- 

 censis Gmel. 1. c, p. 3730. 



A very distinct form, known by the dumb-bell shaped perfora- 

 tion and strong nodose ribs. 



F. barbadensis Gmelin. PL 37, figs. 40, 41, 42, 43, 44, 45, 49 ; pi. 



60, figs. 73, 74, 75. 



Shell conical with oval or ovate base, the apex subcentral, pierced 

 by a small orifice short-oval or almost circular in form. Surface 

 sculptured with radiating ribs of which about eleven are generally 

 stronger, continuing from perforation to the basal margin. 



The form varies immensely, as the figures show. The primary 

 ribs are sometimes very strong, sometimes scarcely more prominent 

 than the others. The ribs are uneven, irregularly serrated in the 

 more coarsely sculptured forms ; in those with subequal, small 

 riblets, the larger ones bear numerous erect, delicate scales. The 

 color is grayish, grayish-green or grayish-pink, often blotched in 

 the spaces between the ribs with purplish-brown. The inside has 



