212 MALACOZOA. TROPIOPODA. LAMELL1BRANCHIAT A. 



1 . Cythercea exoleta. Shell orbicular, subequilateral, 

 moderately convex, with concentric striae, dull yellowish 

 or reddish-white, with radiating reddish or purplish 

 bands. Exoletus, worn. 



2. Cythercea lincta. Shell suborbicular, inequilateral, 

 moderately convex, with fine concentric striae, glossy, 

 greyish-white. Linctus, licked. 



3. Cythercea unddta. Shell suborbicular, convex, 

 thin, with numerous concentric striae and larger rugae, 

 the margin sinuous. Undatus, wavy. 



GENUS 5. VENUS. Shell suborbicular, sub triangular, 

 or cordato-ovate, moderately convex, concentrically stri- 

 ated ; umbones prominent ; three divergent teeth in 

 each valve. Named after the goddess Venus. Linnaeus. 



1. Venus Casina. Shell suborbicular, moderately 

 convex, very thick, with concentric elevated thick entire 

 ridges. 



2. Venus reflexa. Shell suborbicular, compressed, 

 rather thin, with concentric elevated, reflexed, thin- 

 edged ridges. Reflexus, bent back. 



3. Venus Gallina. Shell cordato-trigonal, moderately 

 convex, concentrically lamelloso-sulcate. Gallina, a hen. 



A. V. Gallina laminosa. Covered with plaits. 



B. V. Gallina stridtula. Marked with small streaks. 



4. Venus Prideauxidna. Shell cordato-trigonal, rather 

 compressed, concentrically lamellate. Named after Mr. 

 Prideaux. 



5. Venus fascidta. Shell roundish-trigonal, com- 

 pressed, thick, with broad flattened, smooth, concentric 

 ridges, Fascidtus, banded. 



6. Venus ovata. Shell ovato-triangular, rather thin, 

 divergently ribbed, and reticulated by numerous con- 

 centric striae. Ovdtus, egg-shaped. 



7. Venus trianguldris. Shell subtrigonal, smooth, 

 with three teeth in one valve, and two in the other. 

 Trianguldris, three-cornered . 



GENUS 6. VENERUFIS. Shell ovate or elliptical, very 

 inequilateral, convex, concentrically striated ; umbones 



