ORDER III TELEODESMACEA 417 
Family 32. Petricolidae. D’Orbigny. 
Valves, when not distorted, equal, free, somewhat gaping behind, radiately sculptured 
with plain margins and inconspicuous beaks ; posterior adductor scar larger than the 
anterior, pedal narrow, elongated, distinct ; Vigament and resilium eaternal; area 
obscure or not defined; hinge without lateral laminae, with two or three small, wsuall 
bifid, radial cardinal teeth in each valve. Cretaceous to Recent. 
Petricola, Lam.; Choristodon, Jonas; and Naranaio, Gray, ave the principal forms. 
The family Glaucomyacidae, of estuarine or fluviatile habit, appears to be related 
to Petricola, and includes the recent Glaucomya (Bronn), Woodward, and Tunysiphon, 
Benson. 
Superfamily 13. TELLINACEA. Blainville. 
Siphons distinct to their bases, usually long ; pallial line sinuate ; ligament external, 
seated on nymphs ; hinge normally with an anterior and posterior lateral im each valve, 
two radial cardinals, of which the anterior is commonly bifid and somewhat pedunculated, 
and the posterior, as well as the laterals, often obsolete. 
Family 33. Tellinidae. Deshayes. 
Shell substance cellulo-crystalline, with an inconspicuous epidermis ; valves slightly 
unequal, free, rounded in front, more or less rostrate, oblique, and gaping behind, com- 
pressed, usually with smooth margins, low beaks, and variable, chiefly concentric sculpture ; 
anterior adductor scar larger, frequently irregular ; pedal distinct ; resiliwm embraced in 

Fic. 767. 
Tellina rostralina, Desh. Eocene Damery, 
near Epernay. 
Fic. 766. Bia. 768. 
Tellina planata, Lam. Miocene; Ptzleins- Tellina (Linearia) biradiata, Zitt. Upper 
dorf, near Vienna. Cretaceous ; Gosau, Austria. 
the ligament, sub-external ; area narrow, small, covered with a dark epidermis, or fre- 
quently obsolete; hinge plate narrow, anterior laterals approximate, posterior more 
distant from the cardinals, when present; cardinal teeth small; pallial sinus deep, 
discrepant im the opposite valves. Jura to Recent. 
Tellina, Linn. Elongated, the rostrum more or less twisted ; two lateral teeth in 
each valve. Jura to Recent. 
Sub-genera: Jedlina s.s. (Figs. 766, 767), Tellidora, Morch; Strigilla, Turton ; Linearia, 
Conr. (Arcopagia, d’Orb.), (Fig. 768), ete. 
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