392 



MOLLUSCA 



SUB-KINGDOM VI 



internal, with a strong lithodesma ventrally ; area obscure or absent ; a depressed false 

 lunule before the beaks; valves closed, pallial sinus shallow, obscure; siphons short, 

 separate; marine. Tertiary to Recent. 



Pecchiolia, Menegli. Shell heavy; beaks spirogyrate, distant; sculpture radial. 

 'Eocene ; Alabama. Miocene ; Europe. 

 Euciroa, Dall. Eecent, abyssal. 



The genera Verticordia, Wood.; Trigonulina, d'Orb. ; Haliris, Dall; and ? Allo- 

 pagus, Stol. (Hippagus, Desh. non Lea), are included under the family Verticordiidae. 

 Tertiary and Recent. 



Family 14. Poromyacidae. Dall. 



Shell rounded, nacreous, and ceUulo-crystalline, granular, or smooth externally ; hinge 

 with obscure tubercles in front of the resilium ; ligament external, opisthodetic ; resilium 

 sub-internal below the ligament, with a small lithodesma ; area obscure or absent ; a 

 depressed false lunule in front of the beaks ; valves nearly or entirely closed ; pallial 

 sinus small or obsolete ; marine. Cretaceous to Recent. 



Liopistha, Meek (Cymella, Psilomya, Meek), (Fig. 698). Equi valve, oval, thin, in- 

 flated, concentrically or 

 radially striated, gaping 

 and compressed behind ; 

 beaks prominent, in- 

 curved ; hinge with a 

 nymph and projecting 

 process on each side ; 

 ligament sunken, partly 

 external. Cretaceous. 



? Basterotia, Mayer 

 (Eucharis, Recluz non 

 Peron). Valves sub-equal, closed, with a strong tooth in the right and two in the 

 left ; surface granular ; form trapezoid. Miocene and Recent. 



Poromya, Forbes (Embla, Loven). Ovate, plump, surface granular ; pallial line 

 irregularly widened, not sinuate. Eocene and Recent. 



Dermatomya, Dall. Surface smooth, with a conspicuous periostracum ; pallial 

 line sinuate. Recent, abyssal. 



Cetomya, Cetoconcha, Dall (Silenia, Smith). Recent, abyssal. 



Liopistha frequens, Zitt. 



FIG. 698. 

 Upper Cretaceous ; Gosau, Austria. 



Family 15. Cuspidariidae. Dall. 



Shell sub-equivalve, rostrate, earthy, or cellulo -crystalline, rarely with surface granula- 

 tions ; hinge edentulous or with sub-umbonal tubercula- 

 tion, sometimes buttressed ; ligament sub-internal, anterior 

 to the beaks or obsolete ; resilium internal, with a mesial 

 or ventral lithodesma ; area amphidetic or obscure ; valves 

 closed except at the tip of the rostrum; pallial line 

 simple; siphons united; marine. Jura to Recent. 



Cuspidaria, Nardo (Neaera, Grav), (Fig. 699). Shell Fl0 ' 



f- n j i ;/ 11 . i Citsmdaria eutpidata, Olivi. Mio- 



concentrically sculptured ; hinge with a small posteriorly cene ; 7 Baden, near Vienna. Vi- 



inclined chondrophore in each valve, and an elongated 

 ridge behind it ; ligament always anterior to the beaks 

 Recent. 



when present. Jura to 



Sub-genera : Cardiomya, Adams ; with radial sculpture and a posterior lateral tooth in 

 the right valve. Leiomya, Adams ; smooth, with an anterior cardinal in each valve, and 



