40 ACM.'KA. 



.4. melanostida Carpenter, in Mas. Smithsonian Institution, 

 not P. melanosiicta Gmel., Syst, Nat. xiii, p. 3724; founded on Die 

 weisse grmi gestralilte und schwartz pandirte Napfschnecke of 

 ScHRCETER, Eiuleitung in die Conchylienkenntniss, ii, p. 497, t. vi, 

 f. 9, an unidentifiable but certainly different Aemn'a. 



The young or half grown are often prettily flecked with light 

 brown v-shaped or zigzag markings, most distinctly seen on the in- 

 side (fig. 73). The rays are sometimes absent, and are usually 

 obscure on unworn adult specimens, which are dull and lusterless 

 outside. My figures are drawn from the types in the Smithsonian 

 Institution. 



The strife are more even, more obsolete than in A. candeana; the 

 apex is more elevated, more anterior, the coloration is of a different 

 pattern, and the internal border is narrower, and either unspotted or 

 with fewer spots than in the candeana. 



The synonymy given above is merely nominal, and is introduced 

 only to explain the labels given by Carpenter to the specimens in 

 the Smithsonian and probably in other collections. Anyone who 

 suspects that this is the melanostida of Gmelin, after a perusal of his 

 descrij^tion, may consult the reference in Schroter, and be satisfied 

 that it. is not. Gmelin's diagnosis was comjiiled from Schroter's. 



A. LEUCOPLEURA Gmelin. PI, 5, figs. 16-26. 



Shell solid, rounded-oval, erectly conical or depressed, the apex 

 snbcentral ; surface sculptured with about 12 strong primary ribs, 

 but large specimens have 20 to 30 ribs around the base, the number 

 being increased by the interposition of interstitial ribs, not reaching 

 to the apex. Ribs white, interstices brown or black. 



Inside white Avith a narrow gray border usually black dotted, the 

 central area brown or outlined with brown. 



Length 23, breadth 18, alt. 9 mill. 



Southwest Florida to Guadeloupe. 



Patella lencop/eura Gmel., Syst. Nat. xiii, p. 3699, no. 34. — Lam.j 

 An. s. Vert, vi, p. 332. — Acmcea melanolenca Dale (not Gmelin), 

 Catal. Mar. Moll. S.-E. U. S. p. 156.— P. albicosta C. B. Ad., Proc. 

 Bost. Soc. N. H. ii, p. 8, 1845. — P. albicostata Rve., Conch. Icon. f. 

 128, 1855.— -P. balanoides Rv., I. c, f. 137.— P. occidentalis Rv., 

 I. c, t'. 135.—.^ P. cimeliata Rv., I. c, f. 116. 



There is considerable variation in this species, but it is always 

 much more coar.sely ribbed than A. euhensis Rve. The extremes 



