69 



72. P. lividus. (pi. xiii. f. 61. pi. xiv. f. 89 et 91.) Lam. 

 Anim. s. Vert. vi. p. 1/8. P. sulphureo, Lam. et Ost. Tegulo. 

 Wood, inclusis. 



T. irregulari, sub-ovali, sub-sequivalvi, compressa, foliacea ; 

 auriculis inaequalibus, magnis, anticis majoribus, valvee dextra?, 

 antica validissinie einarginata ; costis 16 ad 20, insequalibus 

 vix elevatis, squamas numerosas, acutas ferentibus; interstitiis 

 irregulariter radiatim sulcatis : colore, fusco variegato, squa- 

 mis luteis vel albis ; variat fusco paululum variegato, squamis 

 fere obsoletis; variat quoque sulphureo. Long. 2. 5.; lat. 0. 

 70 ; alt. 2. 25 ; poll. 



An irregular, compressed, foliaceus species, with 16 to 20 

 irregular, unequal ribs, having numerous thin scales which are 

 nearly obsolete in some varieties ; the ribs of the lower valve 

 are more numerous. The general colour is variegated purplish 

 brown, with the scales white or yellow; there is a variety scarcely 

 .mottled, and another of an uniform sulphureous tint. 



Red Sea and Japan. 



73. P. sqiiamosus. (pi. xiii. f. 48, 49, 50. pi. xiv. f. 88 3 

 92, 93.) Gmel. O. anonyma, Lam. et P. hybridus, Lam. inclu- 

 sis, O. hybrida, Gmel. exclusa. P. arausicanus, Chemn. 



T. irregulari, sub-ovali, sub-ccquivalvi, complanata, foliacea; 

 auriculis imequalibus, magnis, anticis majoribus, valva; dextrce 

 antica validissinie emarginata ; costis 12 ad 18, fere obsoletis, 

 squamiferis, ad umbones evanidis, valvee dextra? numerosis, 

 paululum angulatis ; colore vario, aliquando prope umbones 

 albo fulgurate. Long. 1. 85.; lat. 0. 50.; alt. 2. 10. ; poll. 



The figure in Lister referred to by Gmelin, leaves no doubt 

 of the identity of this species, which is remarkable among 

 the irregular foliaceus group, for a peculiar flatness, particu- 

 larly at the umbones. The varieties are numerous, many of 

 them being marked with fine zigzag lines of white. 



Northern Ocean. 

 And also brought from the Philippines by Mr. Cuming. 



74. P. serratus. (pi. xiii. f. 56.) nob. 



T. oblique ovali, irregulari, postice sub-producta, sub-corn - 

 pressa, auriculis inajqualibus, posticis minoribus, costis nume- 

 rosis, minutissime squamiferis ; colore sulphureo, maculis 

 magnis, fuscis, variegato, intus ad marginem purpureo. Long. 

 1. 20.; lat. 0. 50; alt. 1. 40; poll. 



More ventricose, more oblique, with the auricles smaller 

 and the scales more minute than P. squamosus. Brought 

 from the Philippine Islands by Mr. Cuming. 



75. P. irregularis, (pi. xiii. f. 51-2.) nob. 



T. oblique ovata, irregulari, sub-eequivalvi ; auriculis in- 



