930 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



1887; Grotriania Speyer, 1860; Digitaria S. V. Wood, 1853; Woodia 

 Deshayes, 1860; Rictocymn Dall, 1872; i?/itf<"i^r>6'ymr/ Von Martens, 1871; 

 (loodiilJla Turton, 1822; 2f((cfr!na Brown. 1827; M!cr(>!<f(i<j<»i Coss- 

 niann, 1896; Creniviargo Crcs.sniann, 1903, 



Lig'ainoiit cMifolding the resiliimi, both external, on narrow nynii)hs. 



.... T^ . ,^ . LO.101010.1 , .,„ . , 



^ecixon Ai<tarte B. s. Dental tornni la •>. ()i()ini ()•> the middle noht 



and two left anterior cardinals strong, the others obsolete; valves with 

 convex uni])ones, sn])equilateral, the inner niargins crenate when full}' 

 developed. Type, Astarte sulcata (Da Costa). 



Section Truhynta Schumacher. Like Astarte^ l)ut the inner maroins 

 always smooth. Type, T. horealls Schumacher, 1817. 



? Section ]^c(>eraf<^)n(( Fischer. Like Astarte^ but the uni})ones 

 nearly terminal in front. Type, A. (Mtqua Deshayes. Bajocien 

 Oolite. 



Section Rlctocyma, Dall. Small, like Astarte^ but the valves with 

 irregular bitid or broken sculpture; inner margins not crenate. Type, 

 A. esqariiialfi (Baird). 



Section AsJdarotha Dall, 1903. Umbones concentrically sculptured 

 and conspicuoush" flattened; disk smoother outside of the flattened 

 area; otherwise like Astarte. Type, Astarte undulata Say, Miocene, 

 A. Mpartita Sowerln^ 1829, appears to ))elong here. 



Section Gonilia Stoliczka, Small, lentiform, hinge as in Astarte; 

 disk with divaricate ribbing centrally. Type, Luclna hijxirttta Phil- 

 ippi, 1839 { — Astarte hlpartita Stoliczka, 1871, not of Sowerby; = 

 Astarte calUglypta Dall, 1903). 



Section Digitaria S. V. Wood. Valves rotund, shell small, lenti- 

 form, hinge as in GonUla^ having the larger cardinals bifid; surface 

 obliquely, arcuately sulcate, the sulci grooving more or less the inner 

 margin tangentially; Woodia Deshayes is synonymous. Type, Tellina 

 digitaria Linnaeus. 



Section Crenimargo Cossmann. Shell like Digitaria, but the sur- 

 face smooth; the tangential sulcations of the inner margin are, how- 

 ever, retained as in TransenneJla ; hinge as in Digitaria. Tvpe, 

 C. huvquicrenata Cossman, Parisian Eocene. 



Subgenus Goodallia Turton, Shell small, smooth, the hinge teeth 

 reduced by the absence of the anterior or posterior right cardinal or 

 both of them; inner margins crenate at resting stages only; dental 



formula j?i oioT)" ^^^P^' ^^^'^^t'''^^ triaiigidaris Montagu. Mactrina 

 Brown is synonj-mous. 



Section Microstagon Cossmann, Like Goodallia., but the hinge 

 usually with one or both laterals obsolete and a small (usually ante- 

 rior) right cardinal present, which is not found in Goodallia proper. 



