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, Menegh. Shell heavy; beaks spirogyrate, distant ; sculpture radial. 
Eocene ; Alabama. Miocene; Europe. 
Euciroa, Dall. Recent, abyssal. 
The genera Verticordia, Wood.; Trigonulina, VOrb.; 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 cellulo-crystalline, granular, or smooth externally ; hinge 
with obscure tubercles in front of the resiliwm ; ligament external, opisthodetic ; resiliwm 
sub-internal below the ligament, with a small lithodesma ; area obsewre 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). Equivalve, 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, Lovén). Ovate, plump, surface granular; pallial line 
irregularly widened, not sinuaté. Eocene and Recent. 
Dermatomya, Dall. Surface smooth, with a conspicuous periostracum ; pallial 
line sinuate. Recent, abyssal. 
Cetomya, Cetoconcha, Dall (Silenia, Smith). Recent, abyssal. 

Fic. 698. 
Liopistha frequens, Zitt. Upper Cretaceous ; Gosau, Austria. 1/;. 
Family 15. Cuspidariidae. Dall. 
Shell sub-equivalve, rostrate, earthy, or cellulo-crystalline, rarely with surface granula- 
tions ; hinge edentulous or with sub-wmbonal 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, Gray), (Fig. 699). Shell izae HG: C0 
= 4 ° e : A Cuspidaria cuspidata, Olivi. Mio- 
concentrically sculptured ; hinge with a small posteriorly cone: Baden, near Vienna. 1/). 
inclined chondrophore in each. valve, and an elongated 
ridge behind it; ligament always anterior to the beaks when present. Jura to 
Recent. 

Sub-genera : Cardiomya, Adams ; with radial sculpture and a posterior lateral tooth in 
the right valve. Zeiomya, Adams; smooth, with an anterior cardinal in each valve, and 

