472 MOLLUSCA phylüm vi 



Trapezium Huiniili. emend. Megerle {Lihitina Schiiin . ; Gypricardia Laiii.), Shell 

 elongate, traj^ezoidal, coiicentrically, or luore rarely radially sculptured, often with a 

 posterior keel ; three cardiiial teetli in each valve, tlie posterior in tlie right valve 

 often bifid. Jura to Eecent. 



Plesiocyprina Munier-Chalm. Jura. Gicatrea Stol. Cretaceous. Goralliophaga 

 Blainv. Tertiary and Recent. 



Ärctica Schum. (Gyclas Brug. ; Gyprina Lam.) (Fig. 751). Oval or rounded, in- 

 flated, concentrically striated ; beaks prominent, curved, cardinals three in each valve, 

 the left posterior often bifid, the middle left cardinal largest, and tlie posterior ridge-like. 

 Abundant in the Jura and Cretaceous, and represented by one or two living species. 



Venilicardia Stol. (Fig. 752). Cretaceous. Pygocardia Mun.-Chalm. Tertiary. 



Veniella Stol. {Venilia Morton; (?) Goniosowa Conr.) (Fig. 753). Left valve with 

 the anterior cardinal strong, sub-triangular. Cretaceous and Tertiary. 



Superfamily 2. ASTARTACEA Dali. 



Lohes of the mantle free ventrally ; lateral laminae ohscure, wlicn present distant 

 from the cardinals. 



Family 3. Curtonotidae Dali. 



Shell short and heavy, with suh-terminal heaJcs ; valves free, eqnal, closed ; area 

 ohscure ; ligament as in the Astartidae ; adductor scars, especially the anterior, deep ; 

 pallial line simple ; hinge plate hroad, vnthout lateral laminae ; the formula of the 



cardinals ^ttt-i^j or uTttt- Devonian and Carboniferous. 



This group is inserted conformably with the opinion of Neumayr, wlio regards it as the 

 radical of the Astartidae. 



Gurtonotns Salter. Oval, cardinal border thick, with one very strong tooth in the 

 left, and a strong anterior and thin posterior tooth in the right valve. Scars of the 

 adductors strong, especially the anterior. Devonian ; England. 



Prosocoelus Keferst. Devonian. Protoschizodus de Kon. Carboniferous. 



Family 4. Astartidae d'Orbigny (emend.). 



Shell suhstance cellulo-crystalline, with a pronounced epidermis ; shell rounded or 



suh-triangular, usually with concentric or not radial sculpture ; valves equal or suh-eqnal, 



free, closed ; area distinct ; ligament and. resilium external, parivincular, opisthodetic ; 



heaks prosocoelous ; adductor scars sub-equal, with a distinct anterior pedal scar ; pallial 



line simple; hinge plate distinct, hinge with anterior and posterior 



lateral teeth and their respective sockets, usually more or less obsolete; 



cardinal teeth not bifid at the summit, the terminal teeth frequently 



obsolete. Lobes of the mantle free ventrally, not produced into siphons. 



Pio. 754. Trias to Recent., 



Middle Jura; Gun'- Astarte Sow. (Grassina Lam.) (Fig. 754). Roundly triangulär or 



dershofen, Aisace. oval, rather compressed, thick ; smooth or concentrically sculptured ; 

 l^mule impressed ; right anterior cardinal strong. 



A nmnber of genera have been associated with Astarte which probably belong elsewhere. 

 The following subgenera, however, are Avorthy of recognition ; Coelastarte Böhm, Freconia 

 Stol. ; Crassinella Bayle, non Gnppy (Fig. 755); rroroMa Biilini. Jura. Eriphyla Gabb. 

 Cretaceous. Grotriania Speyer ; Goodallia Turton (Yhj,. 1()1) ; Uhcdocyvm Dali ; Diqitaria 

 Wood (Fig. 756). Tertiary and Recent. 



