74 



aurantiacis ; variat aurantiaco, aibo-maeulato, atque purpureo. 

 Long. 3. 5.; lat. 0. 92.; alt. 3. 5.; poll. 



This well-known species is remarkable for the three rows 

 of thin, sharp, scales upon each rib. South Seas. 



88. P. spiniferus. (pi. xx. f. 229, 230.) G. B. Soiverby, 

 Senr. Zool. Proc. 1835. 110. P. pulcherrimus, Gray, 

 Beechey's Appendix. 



"T. subovata, depressiuscula, subfequivalvi, aequilaterali, 

 auriculis intequalibus, sinistra majore ; valvis radiatim costatis, 

 costis utriusque valv«? novem, latis, squamuliferis, squamulis 

 fimbriatis ; valvee alterius marginibus dorsali, antieo, posticoque 

 spiniferis. Long. 0. 9. lat. 0. 25. alt. 0. 9." 



A richly sculptured little species, from Lord Hood's Island. 



89. P. Tranquebaricus. (pi. xii. f. 12. 13.) Gmel. 

 p. 3328. 



T. ovali-subtrigona, ventricosa, fequivalvi, requilaterali, 

 crassa, : auriculis imequalibus sulcatis ; posticis mediocribus, 

 rectis ; anticis majonbus, acutis : costis 18, subkevibus, ele- 

 vatis, subquadratis, lateribus minutissime serratis : colore 

 pallidissime fulvo, maculis magnis fuscis irregulariter fasci- 

 atim A'ariegato ; vel aurantiaco, immaculato. Long. 1. 35; 

 lat. 0. 60. ; alt. 1. 40. 



Somewhat triangular, ventricose, equivalve, equilateral, 

 thick: with unequal ears, the anterior large; ribs 18, smooth 

 on the tops, very finely striated at the sides. The usual 

 colour is nearly white, with large, defined, brown patches. 

 An orange variety is not uncommon. Tranquebar. 



90. P. Singaporinus (pi. xiii. f. 55. pi. xiv. f. 71.) nob. 

 T. rotundato sub-trigona, sub-compressa, eequivalvi, eequi- 



laterali, sub-tenui ; auriculis imequalibus ; anticis magnis ; 

 costis 24, elevatis, sub-quadratis, ltevibus : colore albo pallide 

 roseo tincto radiis 4, latis, fusco lineatis ; prope umbones 

 griseo maculato. Long. 1. 30. ; lat. 0. 40.; alt. 1. 30. 



Differing from the preceding in being more depressed, and 

 rounded, and having a much greater number of less elevated 

 ribs ; the auricles, although unequal, are less disproportionate. 

 Var. f. 55. Mr. Norris's collection; Var. f. fl, Mr. Cuming, 

 Singapore. 



91. P. Senatorius (pi. xvii. f. 151 and pi. xviii. f. 188 

 to 192.) Gmel. p. 3327- ostraca porphyria ? citrina ? aculeata ? 

 Gmel. P. florens, Lam. (f. 188) P. aurantius, Lam. 



P. ovali sub-trigona, sub-depressa, sequivalvi, sub-laevi ; 

 latere postico paululum expanso : auriculis inEequalibus ; 

 scabroso-sulcatis ; posticis plerumque obtusis; anticis elongatis, 



