20 nuculidjU. 



then rather quickly compressed, subretusc before the convex um- 

 bonal r!dt;'e, white, concentrically lyrated throughout (dorsal areas 

 excepted) ; lyrfe depressed and shelving anteriorly, rather distant 

 on the umboes, close near the circumference; their intervals 

 simple. Sides equal, or very nearly so ; the anterior one sub- 

 attenuated and subangulately rounded at its extremity ; the pos- 

 terior one angular, beaked, its tip fine and convex. Dorsal slopes 

 rather slight ; the front one plano-convex ; the hinder straightish, 

 yet a little disturbed by the pouting of the lunular lips. Ventral 

 margin much rising at both ends, briefly subretuse before the 

 posterior tip. Dorsal areas strongly impressed, sharply detiued : 

 the escutcheon large, adorned at its retuse circumference with 

 rather distant slanting lamellar wrinkles, which become close and 

 longitudinal centrally. Sides of the lunule furnished with slant- 

 ing linear tubercles (or tubercular wrinkles), which do not reach 

 the sutural edge. Teeth rather numerous on both sides. 



33. L. EBURNEA, Sowerhy, f. 90. — T. sequilaterahs, ventricosa, 

 antice semielliptica ; postice acuminata vixque recurvata ; undique 

 sulcata, cute nitidfi pallide olivaceo-lutescente induta ; radii im- 

 pressi plicseque umbonalis fere expers. Margo dorsalis posticus 

 retusus ; ventralis postice multum acclivis. Area profunde im- 

 pressa, longitudinaliter lirata. Lunula lanceolata, linea circum- 

 scripta, concentrice costellato-rugosa. — Twice as long as broad, 

 almost, if not quite, equilateral, semielliptic in front, sharply acu- 

 minated behind, ventricose, (almost tumid at the umboes, mode- 

 rately compressed posteriorly,) clothed with a shining pale yellow- 

 ish-olive epidermis, with only a very faint indented ray, and a 

 scarcely raised umbonal ridge, which is nearly smooth above. 

 General surface regularly sulcated throughout : the interstitial 

 spaces, which anteriorly are shelving, elevated posteriorly into 

 converging lyrae. Hinder peak sharp, subcentral, scarcely up- 

 turned. Dorsal margin convex in front, retuse behind : ventral 

 margin much arcuated in front, straighter and much rising behind, 

 without marked posterior refusion. Lunule lanceolate, linearly 

 defined, with concentric costellar wrinkles : escutcheon angularly 

 defined, deeply impressed, lyrated lengthways. Hinge-margin 

 broad. Teeth numerous on either side of the minute triangular 

 cai'tilage-pit, more so in front. 



3-i. L. FULGiDA, A. Adams, f. 91. — T. Eequilateralis, oblongo- 

 acuta, antice tumida, tevis, cute pertenui polita cinereo-lutescente 

 vel ohvaceo-lutescente induta, radii impressi plicseque umbonalis ex- 

 pers. Extremitas postica angusta, subrecurvata, rotundato-angu- 



