242 AXEL A. OLSSON 



Range — Panama southward to Ecuador. Panama: El Lagartillo, Las 

 Tablas. Ecuador: Santa Elena. 



Ensitellops hertleinl Emerson and Puffer Plate 36, figure 9 



Ensitellops hertleini Emerson and Puffer, 1957, American Museum Novitates, No. 1825, 

 pp. 21, 22, fig. 2. 



Shell very transversely elongate; anterior margin obHque and ventrally 

 rounded; exterior surface ornamented with numerous pustules. Shell small, 

 thin, elongate, solenoid in outUne, inequilateral, small beak in anterior 

 quarter; posterior end rounded, anterior end obliquely truncated, with ven- 

 tral portion attenuated and terminally rounded. Exterior surface sculptured 

 with irregularly spaced concentric growth lines and scattered spinelike 

 pustules, most commonly on the ventral-posterior portion. Prodissoconch 

 small, unsculptured, prominent, raised, turned obliquely to the transverse 

 axis of mature shell. Hinge typical for the genus. Color of shell: exterior 

 dull chalky white; interior glossy white. 



Length 9.5 mm., height 3.0 mm. (Emerson and Puffer, 1957.) 



The measurements suggest that this is a much larger species than the 

 preceding. 



Range — ^West coast of Mexico. Mexico: Guaymas Harbor, four meters 

 depth, Sonora. 



Genus BASTEROTU Hoernes, 1859 



{Eucharis Recluz, 1850. Type species, Corbida quadrat a Hinds) (Not 

 Eucharis Latreille, 1804). 



Type species by monotypy, Basterotia corbuloides Hoernes. Miocene 

 of Europe. 



Shell small, subquadrate corbuliform, with a sharp angle or carination 

 running from the beak posteriorly. Valves convex and usually solid, white, 

 the beaks prosogyrate. Surface marked with fine concentric lines of growth 

 and a sprinkling of fine or coarse granules. Ligament external, attached to 

 a short, stout, platelike nymph. Hinge with a large, hook-shaped cardinal 

 tooth in each valve, bordered behind or in front by a deep socket; in the 

 right valve, the socket lies in front of the tooth and in the left valve behind. 

 There is no pallial sinus. 



Basterotia (Basterotia) qnadrata (Hinds) 



Co'bula quadrata Hinds, 1843, Proc. Zool. Soc. London, p. 57.— Hanley, 1842-1856, 

 Catalogue Recent Bivalve Shells, Appendix, p. 345, pi. 12, fig. 36 West Indies. 

 —Reeve, 1844, Conch. Icon., vol. 2, Corbula, pi. 5, fig. 40. Hab. ---? 



This species has been cited as a Pacific shell by Dall but without men- 

 tion of locality station. Hanley recorded its locality as from the West Indies; 

 Reeve — as unknown. The occurrence of this species in the eastern Pacific, 

 therefore, remains unverified. 



Subgenus BASTEROTELLA Olsson and Harbison, 1953 

 Type species by original designation, PleurodesTna floridana Dall. Plio- 

 cene of Florida. 



