NO. 1704. A COLLECTION OF SHELLS FROM PERU— BALL. 159 



CYRENA ISOCARDIOIDES Deshayes. 



Plate 26, fig. 4. 



Cyrena isocardioides Deshayes, Proc. Zool. Soc. of London for 1854, p. 22. — 

 Prime, Smiths. Misc. Coll. No. 145, 1865, p. 25. 

 Llurona. Tumbes region, from the Estero Bendito. West Colombia, Deshayes. 

 These shells were found in some numbers barely covered by the muddy sand and 

 rather high above low- water mark. The animal contains such a quantity of salt 

 water as to be very unpalatable, even if the flesh be repeatedly punctured while 

 roasting. 



Shell much inflated, rounded trigonal, cordate, thin; anterior end 

 evenly rounded; posterior side obliquely decHning, subtruncate at 

 the extremity; surface smooth except for incremental lines; perio- 

 stracum thin, velvety, of an ohvaceous brown; beaks large, swollen, 

 incurved ; shell white with faint violet streaks ; hinge plate very narrow, 

 teeth small, nearly equidistant from the cardinals; valves white 

 inside, "wdth sometimes a little violet near the margins, which are 

 entire. Pallial line entire, without the sinus found in other American 

 Cyrenas. 



DONAX ASPERA Hanley. 



Plate 28, fig. 7. 



Donax asper Hanley, Proc. Zool. Soc. of London for 1845, p. 14. — Sowerby, 

 Thes. Conch., vol. 3, 1862, p. 307, pi. 1, fig. 24. 

 Almejas. Found at the sand beach of Santa Lucia, mouth of the Tumbes River. 

 A small but esteemed comestible, abundant on many beaches. 



Distribution. — Central America and southward to Tumbes, Peru. 



Shell triangular, wedge shaped, small, solid, wliite or purple; 

 radiately striate in front ; on the short posterior side granulated near 

 the angle of the truncation; behind the angle striated; posterior ven- 

 tral margin denticulate; posterior area convex below, concave above; 

 beaks elevated, the anterior dorsal slope steep. 



The color, as in most donaces, is very variable. On the Lower 

 Californian coast shells of this genus, even smaller than D. aspera, 

 are washed, thrown, shells and all, into hot water, boiled until the 

 juice is extracted and then strained out, leaving a clear broth of 

 which the flavor is liighly praised. 



IPHIGENIA ALTIOR Sowerby. 



Plate 25, fig*. 8. 



Capsa altior Sowerby, Proc. Zool. Soc. of London for 1832, p. 96. — Roemer, 

 Mon. Donax, 1869, p. 114, pi. 21, figs. 1-4. 

 Playeras. From the flats at Capon, 4 to 6 inches deep in the sand, and from a tidal 

 lagoon at La Boca Grande, Tumbes. 



Distrihution. — Gulf of CaHfornia and southward to Tumbes, Peru. 



Shell subtriangular, oblong, arcuate, pale green or rosy under an 



oUve periostracum, internally violet ; posterior dorsal margin sloping, 



