PISSURELLA. 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. PI. 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 ])oints 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. virescem), 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. 



