100 AXEL A, OLSSON 



Anadara (Esmerarca) reinharti (Lowe) 



Plate 8, figure 4; Plate 9, figure 1; Plate 10, figures 4-4d 



Area (Anadara) reinharti Lowe, 1935, Trans. San Diego Soc. Nat. Hist, vol. 8, No. 6, 



p. 16, pi. 1, figs. 3a, 3b, 3c "Guaymas". — Hertlein and Strong, 1943, Zoologica, 



vol. 28, pt. 3, p. 157. 

 Anadara (Scapharca) reinharti (Lowe), Reinhart, 1943, Special Paper, Geol. Soc. 



America, No. 47, p. 74. — Rost, 1955, Allan Hancock Pacific Expeditions, vol. 



20, No. 2, pp. 198-200, pi. 13, figs. 18 a-c, 19 a-b; pi. 14, figs. 20 a-c; text-figs. 



85 a-d. 



The shell is large, rhomboid, whitish, with full, convex umbones ending 

 in small, prosogyrate beaks, anterior of the middle and inrolled a little 

 over a rather wide, obliquely triangular cardinal area. Usually, the valves 

 are moderately thin so that the ribs show on the inside as shallow furrows 

 which end as deeper, sharp-edged flutes at the margin. The valves are 

 slightly unequal in size, the margin of the right valve extending beyond 

 the other a trifle and the external sculpture is likewise somewhat discrepant 

 as in Cunearca. Ribs number about 25, there are 17 ribs in front of an ill- 

 defined posterior umbonal angle and 7 or 8 smaller, less well-defined ribs 

 behind. The ribs of the left valve are a little stronger, subrectangular in 

 section, and more or less transversely noded, especially anteriorly, their 

 interspaces narrower and flattened; in the right valve, the ribs are 

 narrower and as wide as their interspaces, the latter with some distant 

 cross threading. Periostracum thin, deciduous, with bristles set in the inter- 

 spaces. 



An average specimen measures: length 56.1 mm., height 51.3 mm., 

 diameter 44.5 mm. 



This species was described by Lowe from a small shell with a length 

 of only 27.7 mm and of solid texture. When full-grown, the shell reaches a 

 size more than twice as large and the valves are generally quite light in 

 weight. The young shell has been compared with that of A. multicostata 

 but none of our specimens show much resemblance to that species. Its 

 slightly discrepant sculpture and size of the umbones of the valves re- 

 calls species of Cunearca but the noding of the right valve is not so pro- 

 nounced. It is best distinguished by the characters of the ligament and 

 cardinal area as described above for Esmerarca. 



Apparently a common species locally, although seldom or ever obtained 

 on the beach. According to Mr. Harry Johnson, it is the commonest shell 

 obtained by the shrimpers off the coast of Panama. 



Range — Gulf of California to Ecuador. 



Genus LUIfARCA Gray, 1857 



(Argina Gray, 1842, not Argina Huebner, 1918, in Lepidoptera) 

 (Arginarca McLean, 1951 type Area (Arginarca) campechiensis Gmelin) 



Type species by monotypy. Area costata Gray, 1857 (believed to be a 

 deformed specimen of A. pexata Say)=:i4. campechiensis Gmelin. 



Shell medium-sized to large, ovate-oblong, subequivalve, inflated, the 

 umbones and beaks placed at the anterior one-quarter. The cardinal area 

 is long and narrow, placed entirely behind the beaks and covered completely 



