142 MAZATLAN BIVALYES 



Hani. Descr. Cat. p. 155; pi. 18, f. 39. B. M. Cat. D'Orl. 

 Moll. p. 81, no. 725. C. B. Ad. Pan. Shells, p. 258, no. 416. 

 = (Teste Krauss, Sudafr. Moll. p. 16) Area squamosa, Lam. 

 An. s. Vert. vi. p. 474, no. 35. Hani. Descr. Cat. p. 158. 

 = (teste Desk.) Area Domingensis, Lam. A. s. V. vi. p. 467, 

 no. 16. (differing in colour.) = (teste Desk.) Area clathrata, 

 Defr. A. s. V. vi. p. 478, no. 6, (fossil.) 



Compare Byssoarca divaricata Soiv. Proc. Zool. Soc. 1833, 

 p. 18 : (Area d.) Rve. Conch. Ic. pi. 16, f. 108. (Annaa or 

 Chain Is. attached to stones, Cuming ; W. Indies, B. M.) 

 Comp. Byssoarca pusilla, Sow. Proc. Zool. Soc. 1833, p. 18 

 (Area p.) B. M. Cat. D'Orb. Moll. p. 81, no. 717. (Iquiqui, 

 Peru, on stones at low water, Cuming ; Bolivia, Cobija, 

 Peru, Arica, TfOrbigny.) 



Comp. Area donaciformis, Itve. Conch. Ic. pi. 16, f. 104: 

 Proc. Zool. Soc. 1844, p. 125, (Mozambique Channel, in 

 Madrepore, Hanlcey.) 



This species varies considerably in the fineness or coarseness 

 of the cancellated markings, in the projection or otherwise of 

 the posterior rib, and in the shape, which often approximates 

 B. solida, and is not unfrequently greatly appressed. Liga- 

 ment very narrow, solid, only adhering at the posterior part, 

 whence it makes a slight turn round the umbos, as in B. illota. 

 Hinge teeth rather few, slanting, on unequal lines slightly 

 diverging. Muscular scars prominent, glossy white, as though 

 on a single plate attached to the shell. The pedal chink is 

 perceptible, but very small. These characters include speci- 

 mens from the W. Indies, which are undoubtedly A. squamosa, 

 Lam. also quoted by Krauss from Natal. If, as is probable, 

 the species are identical, the Lamarckian name has priority. 

 Another W. Indian species, probably A. umbonata, A. s. v. 

 p. 462, no. 5., differs in the fineness of the cancellations, and in 

 the ligament which fills a central pit, as in B. solida. The 

 A. pusilla of D'Orb. may be a dwarf var. of the Mazatlan shell, 

 but the Cumingian type appears distinct. A specimen of the 

 typical form measures long. '47, lat. '83, alt. '38. 

 Halj. Mazatlan, Beecheys Voyage : Do. rare, nestling in 

 crevices of large shells ; L'pool Col. Sta. Elena, attached 

 to stones, Cuming. Ecuador, Sta. Elena, D'Orbigny. Sta. 

 Barbara, Col. Jewitt. Taboga ; under stones near low water 

 mark, very rare ; C. B. Adams. Also given from Ld. Hood's 

 Is. and the Marquesas. (A. squamosa.) "JN". Hollande, a 

 1'ile King. Mus." Lamarck. J^atal, Jrauss.(A.. Domin- 



