34 ACMiEA. 



'Patella ceciliana Orb., Voy. Amer. Merid., p. 482, t. 81, f. 4-6.— 

 Gay, Hist. Chil. viii, p. 260, 1854. — L. vlridula Gld., in part, 

 Exped. Atlas, f. 459c, 459d, 459e, and text, p. 354. — P. monticula 

 NuTTALL mss. teste Old., I. c. 



This shell has much resemblance in form to strongly sculptured 

 examples of'^l CHtceaj^erso/ia of California; and it is as variable as 

 that species. Some specimens are so elevated that the height of the 

 cone is equal to the breadth of its base, and others are comparatively 

 depressed. The curious streaks of the central area are very charac- 

 teristic of typical specimens, but in old individuals this is often more 

 or less obscured. Dwarfed specimens before me measure, length 9, 

 width 8 1, alt. 7 mill. They have strongly arched basal side-margins, 

 probably from growing pebbles or small gastropod shells. 



P'igures 17, 18, 19 are D'Orbigny's figures of ceciliana. 



I rank the following described form as a variety : 



Var. suBPERSONA Pilsbry. PL 34, figs. 11, 12, 13. 



Shell the shape of Acmcea persona. Apex curved forward, its 

 distance from front margin i to ^ the length of the shell. Anterior 

 ribs obsolete, ribs at the back and sides 10-12 in number, rounded, 

 sometimes irregular, some of them obsolete. White, with v-shaped 

 or irregularly triangular black markings, the black often predomi- 

 nating, and frequently finely speckled or netted with white dots. 



Inside white with gray and black spotted margin and solid, dark 

 chestnut central area. 



Valparaiso, Chili, southward. 



A. VARIABILIS (Sowerby) Reeve. PI. 34, figs. 1-8. 



Shell short, oval, very much depressed, the apex a little behind 

 the anterior third. Slopes somewhat convex. Surface sculptured 

 with numerous low, close, subequal riblets; gray or of a light green 

 tint, radiately painted with black lines of varying widths in the 

 inteicostal intervals ; edge smooth, even, scarcely modified by the 

 ribs. 



Inside smooth, the muscle-scar white (rarely dark in the young), 

 the central area black, conspicuously mottled with white; border 

 broad, grayish or greenish-white, articulated with black ; tract 

 between border and muscle-scar white, chestnut or blackish-brown. 



Length 32, breadth 26, alt. 5-7 mill. 



ChiU. 



