NO. 1312. , SYNOPSIS OF THE VENERID.E—DALL. 355 



divided, larger in the left valve; umbones pluinp. lioanient deep 

 seated; cardinals large and partly bitid; anterior lateral small, i)apilli- 

 form; inner margins crenate; pallial line with a short rounded .sinus. 



Subgenus Cytherea Bolten, s. s. Type, V<')iii^ pihrprra Liinueus. 



Shell large, reticulately sculptured, the right portion of the escutch- 

 eon produced over the sunken ligament; lateral tooth minute. 



Tropical seas. 



This is Afiiigona Romer, 1857, not Schumacher, 1817. 



Section Clcijusina Brown, 1827. Type, Yenus verrucosa Linnaeus. 



Shell large, strongly concentrically lamellose, with obscure divari- 

 cating radials toward the ends; right portion of the escutcheon not 

 overlapping the ligament; pallial sinus small, narrow, angular. 



Tropical and temperate seas. 



This is Venasiirius (Dumeril) Froriep. 1806 (not binomial); Dosina 

 Gray, 1838; Venim Swainson, 1840, not Lamarck, 1799; Calista (Poli) 

 Leach, 1852, not Morch, 1^3; CalUsta Fischer, 1887, but not Clausina 

 Romer, 1857. 



Section Ventricola Romer, 1857. Tj'pe, VeniLS r^igosa Gmelin. 



Shell large with strong, distant, evenly spaced concentric lamella, 

 between which are smaller concentric threads; pallial sinus small, an- 

 gular, lunule deeply impressed; right part of the escutcheon obsolete. 



Tropical seas of l)oth hemispheres. 



Subgenus Aphrodina Conrad, 1868. Type, Meretrix tijypana Con- 

 rad. Cretaceous. 



Shell concentrically striated, with a circumscribed lunule. but no 

 defined escutcheon; inner margins smooth, pallial sinus ample, free, 

 ascending, rather rounded in front; hinge with three cardinals in each 

 valve, the right posterior cardinal bitid; an elongate anterior lateral 

 corrugated on both sides and received into a pit with similar con-uga- 

 tions; nymphs smooth. 



This form wants the posterior lateral and the granular nymphs of 

 DosiniopHls^ and differs from Cydorisnia by its form, the presence of 

 an anterior lateral and a defined lunule. 



Subgenus Antigona Schumacher, 1817. Type, Cytherea lamellari.'i 

 Schumacher (+ Do.shia lainarckH Gray). 



Shell having the form and sculpture of a CMone (Megerle), but with 

 a lamelliform well-developed anterior lateral entering a socket in the 

 right valve; the posterior right cardinal broad and deeply bitid: pal- 

 lial sinus small, triangular. 



Schumacher's type has been confused with CMone cancellata. but an 

 examination of his figures and references makes his meaning plain. 



Section Antigona s. s. 



Shell rather elongate, with profuse concentric lamellation crenu- 

 lated by fine radial ribs; lunule deeply impressed, the ligament 

 exposed, the overlap of the escutcheon small. 



This is not Antigonm Hiibner, 1816, or Antigona Romer, 1857. 



