FISSURELLA. 171 



Rouss. i, p. 438, t. 53, f. 11-14. F. rosea Gin. PHIL. Enum. Moll. 

 Sicil. ii, p. 91. and of some other authors, not of GMELIX. F. nim- 

 bosa L., SCACCHI, and PHILIPPI, olim. F. lilacina O. G. COSTA 

 Catal. Taranto, p. 42.^. viridis COSTA, 1. c., p. 43, t. 4, f. 1. F. 

 cinnaberina COSTA, 1. c., p. 43, t. 4, f. 4. F. Philippii REQUIEN, 

 Coq. de Corse, p. 40. 



The only Mediterranean species of true Fissurella, the others 

 belonging to the genus Glyphis. It is rather variable in color and 

 form, but is constantly separated from the West Indian F. rosea by 

 the decidedly larger perforation and more obsolete ribbing. The 

 similar South African species have the muscle-impression much 

 nearer to the margin than it is in this form. 



Varieties recognized by Messrs Buquoy, Dautzenberg and Dollfus 

 are as follows : SQUAMULIFERA B. D. & D., radiating riblets bear- 

 ing numerous projecting, imbricating scales. Patras, Greece. Color- 

 forms LILACINA, VIRIDIS and CINNABERINA are sufficiently described 

 by their names. 



Dunker (Ind. Moll. Guin. infer.) has reported the species from 

 Guinea. 



F. MUTABILIS Sowerby. PL 39, figs. 2, 3. 



The shell is ovate or long-ovate, rather thin, higher behind than 

 before, more or less convex, and always sufficiently so that the sides from 

 apex to base are not contracted as in F. incarnata, but are somewhat 

 convex. The orifice is in front of the middle and usually slopes for- 

 ward ; it is always encircled by a rose-red border, narrower front 

 and back, and widest in the middle. The edge is acute and finely 

 crenulated, but generally rubbed smooth. The shell rests upon the 

 entire margin, rarely the front end gaping or elevated a little. The 

 muscle-impression lies near the margin, as in F. incarnata. The 

 inner callus of the orifice is more or less rose-red. There are two 

 color- varieties ; a banded and a marbled. 



The banded form has 12 or 13 reddish-brown rays, the white in- 

 terspaces somewhat narrower ; is somewhat thick, sculptured with 

 radiating riblets, those on the white rays stronger than on the pink. 

 Length 13, breadth 7*, alt. 3 mill. 



The marbled form is grayish or reddish, flecked with darker, 

 very obscurely rayed around the orifice, or with a couple of white 

 interrupted rays in the middle. This form is thinner than the 

 other, more finely striated, more elongated. Length 17, breadth 9, 



