MUSEUM OF COMPARATIVE ZOOLOGY. 243 



treme form of reticulata. In the absence of specimens for comparison, how- 

 ever, the question cannot be fairly settled. It is a shallow-water species, and 

 the material obtained by the " Blake " was all immature or dead. 



Area Adaznsi Shuttlewoeth. 



Area lactea C. B. Adams, non Linne. 



Area ccelata Conrad, Tert. Form. U. S., p. 61, pi. xxxii. fig. 2 (1844), not of Reeve. 



Dredged by Sigsbee oflf Havana in 80 fms. ; and at Station 220, near Santa 

 Lucia, in 116 fms. 



This species is very common in shallow water throughout the "West Indies, 

 and extends northward nearly or quite to Cape Hatteras. Its simulated ribs 

 of trailing blisters give it a remarkably similar appearance to Area lactea, which 

 however has real ribs. There is a dwarf, very short squarish variety, which 

 from its greater proportional diameter (though not otherwise different) would 

 at first be separated as distinct, and which may be called Area Adamsi var. 

 Conradiana. 



Area Noae Likne. 



Area harhadensis D'Orbigny, II. p. 321, as of Petiver. 

 Area occidentalis Philippi, and C. B. Adams. 



A valve of this common form appears in the collection from Charlotte Harbor, 

 Florida, in 13 fms. It is common in shallow water throughout the West Indies. 

 It is possible that the Antillean form may be separable from that of the Medi- 

 terranean, but I have not been able to examine the matter critically as yet. 



Area umbonata Lamarck. 



"What appears to be a dead valve of this species was dredged at Station 282, 

 near Barbados, in 154 fms. It may have been disgorged by a fish. 



Area ectoeomata, n. s. 



Plate VI. Fiffs. 9, 10. 



Shell white, compressed, elongate, equivalve, very inequilateral ; covered with 

 a long, soft, silky red-brown epidermis projecting in ribbon-like strips, which 

 may be broken up into narrow fiat filaments, and project especially at the 

 lower posterior angle of the shell ; valves gaping slightly for the large stout 

 byssus ; external sculpture of narrow, somewhat irregular, minutely nodulous 

 concentric waves ; the interspaces sparsely radiately striate; these stria) and 

 little nodules correspond to thickened radii in the ribbon-like epidermis which 

 are seated on them ; these radii in old shells remain after the flattened web 

 which connected them is worn away, and so give to the older shells the aspect 



