106 TESTACEOUS MOLLTJSCA. 



gibbose, closed posteriorly, the rays spread all over the shell. 

 ^7__ . . \^^,—3Iazatlan. 



C. Radiata. Sow. Z. P. 1835. Sub-triangular, sub-equi- 

 lateral, gibbous, rather pale, rayed and waved with brown, smooth, 

 covered with a more or less thick horn-Hke epidermis ; the sides 

 rounded towards the straightish ventral margin ; no heart-shaped 

 lunule; four cardinal teeth. 2 . . 2|-. — W. Columbia. — Very like 

 Planulata, but the rays are composed of angulated markings. 



C. Crassalelloides. — Trigona. C. Conrad. Journ. A. N. 

 S. Phil. 7. p- 253. t. 19. f. 17. Equilateral, triangular, transverse, 

 thick, convex, depressed, whitish (often rayed with brown), lunule 

 undefined ; anterior extremity truncated ; ligament short, very broad, 

 and elevated ; apex very prominent, beaks not oblique ; cardinal 

 teeth veiy thick and prominent, anterior tooth elongated and thick, 

 the sinus of the palleal scar angular. 7. — California. 



C. Stultorum. — Trigona S. Gray in Analyst. 1838. — 

 DoNAX S. W. S. t. 2.f. 2. Sub-triangular, oval, equilateral, con- 

 vex, rather thick, smooth, glossy, rounded at the sides, ventral edge 

 slightly arcuated ; variable in colouring, sometimes with a single 

 central short white ray on a very pale livid ground, sometimes with 

 broader or narrower livid rays on whitish ground : anterior slope 

 livid : inside white, the lateral and posterior teeth connected. 

 1 . , 1|, — Indian Seas ? S. America ? 



C. CosTATA.— Venus C. Chem7iitz f. 1975.— TT. t. 7. / 39. 

 — D. p. 175. — Young. — C. Erycinella. Lam. Oval, sub- 

 cordate, white, with pale livid rays under a yellowish periostraca, 

 thick, strong, glossy, with transverse broad well raised rather 

 shelving ribs, which are flat above and about twice the breadth of 

 the interstices : lunule elongated, heart-shaped, smooth, and as well 

 as the anterior slope white lineated with livid red : anterior edge 

 obtuse : inside uniform white. 1|^ . . 2,\ — Pacific ? — Closely allied 

 to Erycina but more oval, its ribs distinct and its margin never 

 as in that species stained with orange. 



C. KiNGii.'— Venus K. Gray inW. S.f. 9. Ovate, sub-cor- 



1 An orbicular and usually colourless group seems, with justice, 

 to have been dissevered by Gray, Sowerby, &c. from the genus we 

 have been describing. 



ARTEMIS.-PoLi. 



Orbictdar, edge entire; posterior tooth of the left valve rudimen- 

 tary ; syphonal infiection angular, ascending, acute. 



The following species are described by Mr Gray in his valuable 

 paper on the Cythereanse, in the Analyst for 1838. 



A. Ponderosa. Gray. Orbicular, rather convex, very thick. 



