JOKKS-HKOWNK : SYNOPSIS OF THE VENKHID^. 61 



Shell oval, concentrically ridged. Luuule impressed and circum- 

 scribed. Escutcheon gen(.'rally defined, butnaiTow. Hinge like tliat 

 of Callista, but the pit between the laterals of the right valve is 

 continued into a channel which passes under the anterior cardinal. 

 I'allial sinus deep and horizontal. Right posterior margin grooved, 

 but not the left anterior. Pedal scar opening freely or by a short 

 channel into that of the adductor. 



Section Amiantis, s.s. Type, Cytherea callosa, Conrad. 



Shell thick, glossy, and broadly ribbed over whole or part of surface. 

 Hinge stroug, with rugose nymphs. Pallial sinus generally pointed. 

 This includes only three species, A. callosa, A. umbotiella, Lam., and 

 A. purpurafa, Lam. 



Section Lamelliconcha, Dall. Type, Ci/therea concinna, Sow. 



Shell concentrically ridged. Hinge-plate excavated and attenuated 

 behind. Nymphs longitudinally striated. Pallial sinus obtuse or 

 regularly rounded. The shells known as Bione diune, D. lupanaria, 

 D. rosea, D. circinata, D. unicolor, and D. cor (^Hanley) belong to this 

 section. 



Venus diotie, Linn., ought to have been taken as the type of tlie 

 Lamelliconcha section, but Dr. Uall was under the erroneous 

 impression that Fischer had proposed the name Hysteroconcha with 

 V. dione as its type, whereas he merely mentioned it as a synonym of 

 Gray's Dione. Dall's Lamelliconcha only ditfers in the absence of 

 spines, which I regard as a specific and not a sectional character. 



Genus PiTAHiA, ]lomer, 1857, em. 



This genus was also fully discussed in the article above-mentioned, 

 and reasons were given for establishing the two sub-genera to which 

 I gave the names of Callizona and Leucothea, but it has been pointed 

 out to me that both these names are preoccupied and 1 am consequently 

 obliged to propose substitutes. For the former I propose Tinctora 

 (from tincta and ora, a border), and for the latter Aphrodora (from 

 a(ppo'}, foam, and ^wpa, a gift). I also separated a section under the 

 name of Pitarina. By an oversight, however, the section Ayriopoma 

 was placed under Amiand-'i, instead of under Pitaria, where it properly 

 belongs. The following is an amended synopsis of the genus: — 



Synonym: Caryatis, Romer, 1862. 



Shell oval or sub-trigonal, smooth or finelv striate; lunule super- 

 ficial ; escutcheon not defined. Teeth of the left valve like those of 

 Amiantis, but the posterior cardinal generally more or less separate 

 from the nymj)!! ; in the right valve the two outer cardinals often 

 united to form an arch over the median. P.illial sinus short ami 

 i-ounded. Right posterior and left anterior dorsal margins grooved as 

 in Callista. Pedal scar confluent with that of adductor. 



Section Pitaria, s.s. Type, Venus ttimens, Gmel. 



Nymphs longitudiiuiUy striated. Left posterior cardinal confluent 

 with the nymph, median triangular; right cardinals separate. Pallial 

 sinus deep and pointed. 



Section Ca/pitaria, J.-Bv., 1908. Type, Cytherea sulcafaria, Lam. 



