FISSURELLA. 167 



variety in which the white rays bear much more prominent ribs 

 (pi. 60, fig. 80, 81). This may bear the name of var. sculpta. 



*** 

 Species of the Cape Verde and Canary Is. and adjacent Coasts. 



The genus Fissurella is represented by numerous forms in the 

 Cape Verde Archipelago, but specimens of them are rare in collec- 

 tions. It would be easy to thi'ow a number of the species together, but 

 synonomy made without the examination of large suites is less use- 

 ful than an unprejudiced statement of the facts actually known. 

 All of the species are here for the first time collocated into one group. 

 They are doubtless connected by the bond of common ancestry. 

 The group seems to have been derived, probably at no very ancient 

 date, from the West Indian fauna. 



The species stand thus in the order of publication : 



1. F. coarctata King, 1831. 4. F.alabastritesRve., Aug., 1849. 



2. F. afra Q. & G., 1834. 5. F. glaucopsis Rve., Aug., 1849. 



3. F. verna Gld., Aug., 1846. 6. F. humphreyi Rve., June, 1850. 



7. F. conioides Rve., Aug., 1850. 



F. humphreyi Reeve. PI. 39, fig. 4 ; pi. 60, figs. 88, 89, 90. 



Shell conical, the base oval ; white ; sculptured with numerous 

 (about 40) radiating ribs and riblets, very unequal in size, and more 

 or less obviously nodulous. Summit a little in front of the middle. 

 Fissure oblong, a little over tAvice as long as wide, somewhat con- 

 tracted in the middle, and about one-seventh the length of the shell. 

 Inside pure white ; edge denticulate. 



Length 28, breadth 20, alt. 10 mill. 



Cape de Verde Is. 



F. Humphreyi Reeve Conch. Icon. f. 85, June, 1850. — Sowb., 

 Thes., p. 189, f. 61. 



This form is very closely allied to the West Indian F. nodosa. 

 The radiating riblets are, however, more unequal, and the altitude 

 is less. It is similar to F. alabastrites, but has a smaller fissure and 

 the ribs are swollen at intervals, making them nodose. 



F. alabastrites Reeve. PI. 60, fig. 93. 



Shell conical with oval base, summit a little in front of the middle ; 

 strongly radiately ribbed ; orifice large, about one-fifth the length 

 of shell, contracted in the middle. 



The shell is white, sculptured with about 25 strong radiating ribs, 

 not equal in size. The orifice is sole-shaped, having a dark line 



