FISSURELLA. 159 



Thes. p. 188. f. 37. CARPENTER, Maz. Cat. p. 213. C. B. AD. 

 Panama Sh., p. 238. 



A very solid, conical species, green inside and having a bipartite 

 orifice. The callus around the hole inside is flat, like a little deck, 

 and of a still darker shade of green. The synonomy given above, 

 cannot, I believe, be seriously questioned. The name virescens has 

 priority in Sowerby's original paper. It differs from the form called 

 nigropunctata in being a little more expanded for its height, having 

 the radiating riblets larger and less equal ; uniform greenish-gray 

 without rays. 



Var. NIGROPUNCTATA Sowb. PI. 31, figs. 11, 12, 13. 



Differs in being a little more elevated, the radiating riblets 

 smaller, more equal ; greenish-gray, having about 9 rays, each com- 

 posed of a group of black lines which are usually interrupted into dots. 



Length 43, breadth 32, alt. 20 mill. 



Length 58, breadth 43, alt. 24 mill. 



Panama; Gallapagos Is. 



F. MACROTREMA Sowerby. PL 31, fig. 14. 



Shell ovate, sometimes rather elevated, radiately striately grooved ; 

 orifice elongately oblong, contracted in the middle ; greenish, rayed 

 with brown, red or purple-black ; interior pale green. (Rve.) 



Gallapagos Is. 



F. macrotrema SOWB. P. Z. S. 1834, p. 125 ; Conchol. Illust., f. 41. 

 REEVE, Conch. Icon., f. 31. SOWB., Thes., p. 191, f. 86, 90. 



F. ALBA Carpenter. PI. 45, figs. 1, 2, 3, 4. 



Shell oval, a little narrower in front, conical, summit a little in 

 front of the middle. Perforation oblong, contracted in the middle, 

 about one-sixth the length of the shell, its sides produced upward in 

 little points on either margin of the orifice. 



The form is conical, elevated, with an orifice of the same shape as 

 that of F. virescens. It is solid, white (rarely black-rayed), 

 sculptured with radiating riblets, very variable in size, and usually 

 a little uneven or nodulous. Inside white (or very pale flesh color), 

 rarely with a slight greenish tinge toward the callus. Orifice sur- 

 rounded by a thick callus, (not so flat as in F. viresceni), bounded 

 by a black line ; outer margin crenulated. 



Length 32, breadth 24, alt. 10 mill. 



Length 31, breadth 22, alt. 12 mill. 



Length 27, breadth 17, alt. 11 mill. 



Mazatlan. 



