72 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



Antigona, Schum., 1817. 



Synonyms : Dosina, Gray, 1838 ; Venus, s.s., Gray, 1847, and 

 Deshayes, 1853; Omphaloclathrum, Morch, 1853; Venus (Antiffotm), 

 E. A. Smith, 1885 (Challenger Report); Cytherea, Dall (after 

 Bolten), 1902. 



Shell convex and generallj' globose, with prominent concentric 

 lamellae and sometimes with radial sculpture. Lunuleand escutcheon 

 both clearly defined. Uiubones prominent and incurved. Inner 

 margins creuate. Hinge thick and teeth strong; each valve with 

 three divergent cardinals, of which three are grooved, and the posterior 

 of the left valve is confluent in the nymph. The anterior lateral of 

 the left valve is often small and papillose, and those of the right are 

 obsolete. Pallial sinus short, either angular or rounded. Pedal scar 

 generally sepai'ate from that of the adductor. 



Antigona, s.s. Type, Cytherea lamelUiris, Schum. 



Shell oval, with strong concentric lamellae, crossed by radial riblets. 

 Lunule impressed, and escutcheon defined in both valves. Ligament 

 exposed. Teeth widely divergent, and both anterior cardinals 

 directed forward ; a strong anterior lateral in the left, and two small 

 ones in the right valve. Nymphs long and striated. Pallial sinus 

 small and acutely angular. 



Artena, Conrad, 1870 (= Ventricoloidea, Sacco, 1900). Type, 

 Venus straminea, Conrad, 1842 (not of Conrad, 1837). 



Shell oval, globose, witli shai'p concentric lamellae, and striated 

 interspaces, but no radial ribs. Left anterior lateral well developed, 

 and two strong laterals iti the right valve with a long, deep pit 

 between them. Other teeth normal. Pallial sinus small and angular. 



The tvpe is an Ameiican Miocene fossil. European species are 

 Venus loewyi, Meun. (Oligocene), Cytherea mult i lamella, Lam. 

 (Miocene and Pliocene), Venus burdigalensis, Mayer (Miocene). 



Snl genera. 



Periglypta,' J.-Er,, 1914 (= Cytherea, s.s., Bolten in Dall). 

 Type, Venus puerpera, Linn. 



Shell cancellated by strong concentric ridges crossed by radial riblets 

 which crenulate the ridges. Escutcheon narrow, and the right half 

 overlapping the left. Ligament deeply sunk. Nymphs usually 

 having a tim ly rugose area. Anterior lateral very suudl and close to 

 the anterior cardinal. Pallial sinus usually wide and ruunded. 



This group includes the lollowing species which are currently 

 known as ' Ve?ms^ : V. reticulata, Linn., V. crispata, Desh., V. listeri, 

 Gray (W. Indies), V. clathrata, Desh., V. suiverbyi, Desh. (E. Indies), 

 V. multicostata. Sow., and V. monilifera. Sow. The forms known as 

 lacerata, Hanley, magnifica, Hanley, and reticulata, Sow., are probably 

 only varieties oi puerpera. Two other species, V. laqueata, Sow., and 

 V. chemnitzi, Hanley, differ from all the rest in the following 



^ From irepj, very much ; yXvirros, carved. 



