*S6 AXEL A. OLSSON 



nearly or quite to the front side of the adductor scar; there is no posterior 

 lamina in the right valve, the dorsal margin itself is narrow so that it 

 resembles and may function as a crural lamina and carries along its inner 

 side a grooved depression for the contact of the posterior lamina of the 

 right valve; and below this, another deeper groove which is the resilifer. 

 The resilium is reinforced by accessory plates of the lithodesma. The cavity 

 within the valves is often marked with deep radial rays. 



Fandora (Clidiophora) arenata. Sowerby Plate 81, figures 1-lg 



Pandora arcuata Sowerby, 1835, Proc. Zool. Soc. London, p. 93 Santa Elena. — Sowerby, 

 1855, Spec. Conch., vol. 1, pt. 2, figs. 27, 28. — Sowerby, 187+, Conch. Icon., vol. 

 19, Pandora, pi. 1, fig. 8. 



Clidiophora cristata Carpenter, 1864, Zool. Soc. London, p. 597. 



Pandora cristata (Carpenter), Sowerby, 1874, Conch. Icon., vol. 19, Pandora, pi. 1, fig. 1. 



Pandora claviculata Carpenter, 1855, Proc. Zool. Soc, p. 228. — Sowerby, 1874, Conch. 

 Icon., vol. 19, Pandora, pi. 3, figs. 20a, 20b. 



Clidiophora claviculata (Carpenter), 1864, Proc. Zool. Soc, p. 596. 



Shell small to medium-sized (length up to about 30 mm.), irregularly 

 elongate, the left valve moderately convex, the right concavely depressed. 

 The right valve is divided into two unequal parts (the left valve less 

 clearly so) by an obscure, radial line extending across the umbone to the 

 ventral margin; posterior of this line, the ventral margin shows a slight 

 bulge, anteriorly it is slightly contracted; fresh shells retain the brownish 

 epidermis and the thin outer layer shows this by a change in color. Anterior- 

 dorsal margin with three or more sharp, triangular serrations; in others, the 

 anterior margin is turned over towards the right. 



This is the common Pandora along the coast of Ecuador and northern 

 Peru. According to Carpenter, the original specimens of P. arcuata in the 

 Cumings collection at the British Museum (Nat. Hist.) are too badly worn 

 for a definite determination; however, the obsolete impressed groove men- 

 tioned in the original description and also by Hanley identifies the species 

 easily. Fresh specimens of P. arcuata have three sharp teeth or serrations 

 along the anterior-dorsal margin and it is believed that P. cristata of Car- 

 penter represents the same species. 



Range — Lower California to northern Peru. Panama: Old Panama; 

 Bucaro. Ecuador: Charapota; Manta; Santa Elena. Peru: Tumbez; Zor- 

 ritos; Mancora. 



Subgenus FRENA3ITA Iredale, 1930 



(Coelodon Carpenter, 1864, not Andinet-Serville, 1832, or Lund, 1838, 

 insects). 



Type species by original designation, F. patula Tate. 



The right valve has three, the left valve two crural elements, the an- 

 terior left lamina is shaped like a tent. Internally, the cavity of the shell 

 within the palHal hne is generally marked with radial lines. A lithodesma is 

 absent. 



The typical species of this subgenus are Indo-Pacific and Australian but 

 the following American species may perhaps belong here also. 



Pandora (Frenamya) radiata Sowerby Plate 81, figure 3 



Pandora radiata Sowerby, 1835, Proc. Zool. Soc. London, p. 94 Insulana Muerte. — 

 Sowerby, 1874, Conch. Icon., vol. 19, Pandora, pi. 2, fig. 9. 



