32 ACM^A. 



with thick, narrow radiating and concentric subequal lines, the inter- 

 sections nodose ; margin entire. Has the aspect of Lepeta cceca 

 Miill. Length 6, breadth 4, alt. 2 mill. 



Puntarenas ( W. coast Central America). A single specimen. 

 Differs from L. cceca in the very coarse and close concentric lines, 

 and the numerous finer radiating lines. 



** * 



III. SPECIES OF THE WESTERN COAST OF SOUTH AMERICA. 



Of the following species, I have not seen A. coffea Rv., exilis 

 albescens and nisoria Phil. Of the others, numerous specimens have 

 been examined. 



A. SCUTUM Orbigny. PI. 4, figs. 77, 78, 79, 80, 81. 



Shell rounded-oval, conical, the apex directed forward, nearer the 

 middle than the front margin. Front slope straight, back slope 

 somewhat convex. Surface nearly smooth, but finely radiately 

 striate, the stride obsolete on some specimens. Color black, dotted 

 or spotted more or less profusely with white. Edge of the shell 

 smooth, even. 



Inside white, with a broad black margin (often spotted with white), 

 and a dark brown central tract, which is usually partially or wholly 

 concealed in old individuals by a white layer. Muscle-scar incon- 

 spicuous. Length 40, breadth 35, alt. 15 mill., or less. 



Peru to Sts. of Magellan. 



A. scutum ORB. (not Esch.), Voy. Amer. Merid., p. 479, t. 64, f. 

 8-10. CARPENTER, Amer. Journ. Conch, ii, p. 335. L. punctata 

 GRAY, where? 



Has some resemblance to black forms of A. patina. It is a solid, 

 black species, usually rather conical, more or less dotted with white. 

 Young specimens have the apex decidedly hooked forward, and the 

 central spot dark and prominent. It is a true Acmcea. 



A. VIRIDULA Lamarck. PI. 1, figs. 1, 2, 3, 4, 5, 6. 



Shell rounded-oval, conical, or depressed, the apex in front of the 

 middle. Surface having about 20 low, rather wide radiating ribs, 

 and obscurely, finely striated all over the ribs and interstics. The 

 color-pattern is a close, fine network of light-green on a white 

 ground, the intervals between the ribs with larger spots of green, 



