200 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 20 



reinharti with a length of 21 mm has three grooves, and a specimen 

 43.5 mm long has six; while a specimen of A. multicostata with a length 

 of 75 mm has three grooves, and a specimen with a length of 53 mm 

 has only one groove. The large specimen which, as previously mentioned, 

 was with doubt referred to A. reinharti, has six grooves on the ligament. 

 It may be seen that the number of ribs cannot be used to distinguish the 

 two species with certainty, since this number slightly overlaps. The 

 character may, however, be used as an aid to identification. 



As pointed out by Lowe (1935, p. 16), Anadara reinharti is more 

 inflated than Anadara multicostata. The D/L ratio of A. reinharti in 

 the present material varies between 66% and 87%. The same ratio in 

 the holotype is 88.5%; for its size, the type is exceptionally inflated. 

 Small specimens have the lowest D/L ratio. One tiny eye-spot may be 

 observed on the anterior end of each mantle margin in some specimens ; 

 it is not easily observed and does not seem to be a constant character. 

 The foot is furnished with a threadlike byssus which was intact in many 

 of the specimens examined. In some small specimens (5 to 10 mm), 

 pebbles were attached to the byssus. 



Occurrence: This species was taken from 1 to 50 fms, on various kinds 

 of bottom, sand, shells, rock, mud, etc. Previously (Hertlein and Strong, 

 1943), it was known from the Gulf of California to Panama. Two 

 samples in this collection are from Ecuador. 



Distribution: Punta Pefiasco, Sonora, Gulf of California, to Bahia de 

 Santa Elena, Ecuador. 



Anadara (Scapharca) cumingiana (Nyst) 1848 



Area cumingiana Nyst, Mem. Acad. Roy. Sci. Belgique, vol. 22, p. 22, 

 new name for Area concinna Sowerby 1833, P. Z. S. L., p. 20 (not 

 Cucullaea concinna Phillips 1829). 



Fig.: Maury, 1922, PI. 1, fig. 10. 



Anatomy: Heath, 1941. 



Type loc.: Golfo de Nicoya, Costa Rica; 12 fms; coarse sand. 



Holotype: British Museum? 



Remarks: Unfortunately the specific name cumingiana has to replace 



concinna (Sowerby), according to the International Rules of Zoological 



Nomenclature (see Reinhart, 1943, p. 73, footnote). 



A good description of this species is given by Maury (1922, p. 25). 



The ligamental area is similar to that of Anadara biangulata (Sowerby) 



= gordita (Lowe), a species to which it seems to be related. The 



chevron-shaped ligament grooves are few (one to three) in relation to 



