60 NUCUHD^. 



SOLENELLA, Bowerhy. 



Gen. Char. Longer than broad, not nacreous, gaping at botli 

 ends, with a prominent external Hgament, and a distinct pallial 

 sinus. Hinge witli numerous sharp high teeth on one or both 

 sides. 



Sect. I. SoLENELLA proper. Species 1 and 2. — Oval, thin, 

 unsculptured, with a polished epidermis ; dorsal margin excised 

 for the ligament : paUial sinus very large. Anterior side with 

 very few teeth, but a blade-like continuation of the inner margin. 



Sect. II. '^%\\jo, Adams. Species 3. — Sculptured, the epidermis 

 unpolished. Anterior gape slight. Teeth in a straight line, nearly 

 equally numerous on both sides. 



1. S. NoRRisii, Soioerhy, f. 1, 2. — T. subovata, subsequilateralis, 

 subcompressa, cutenitidissima olivacea induta, sublaevigata, postice 

 (etiamque antice, sed obsoletius) radio lato vix impressa. Extre- 

 raitas lateris antici brevioris angustiorisque, in medio retusa, 

 superne rotundato-subangulata, inferne oblique rotundata. Margo 

 dorsalis uterque vix declivis, antice convexiusculus ; ventralis cou- 

 vexus, antice magis acclivis. Arere dorsales nullfe. Denies an- 

 tici permulti. — Var. Latior, brevior, rugis incrementi conspicuis ; 

 extremitas antica tautum attenuato-rotundata : margo dorsalis 

 utrinque magis declivis. — Subovate, somewhat compressed, gaping 

 very much at both ends, with a polished ohvaceous epidermis that 

 ranges in tint from yellowish to cinereous, merely marked by 

 concentric wrinkles of increase, which in aged examples become 

 almost fold-like near the lower margin ; devoid of umbonal ridge 

 or defined dorsal areas ; marked, in the adult, with an almost 

 obsolete shallow broad indented ray behind, and a still fainter one 

 in front, at whose terminations the ventral margin is indented. 

 Extremity of the anterior side, which is rather, yet decidedly, the 

 shorter and narrower, retuse in the middle, subangularly rounded 

 above, obliquely rounded-off below : posterior end unsymmetricaliy 

 rounded. Dorsal slopas slight ; front one plano-convex, rather 

 the more decided : hinder one excavated for the ligament. 

 Ventral margin convex, more rising in front. Teeth extremely 

 fine, very numerous in front, scarcely any behind. — Var. brevior. 

 Shorter, broader, and with the slopes consequently rather more 

 decided ; wrinkles of growth numerous and conspicuous : anterior 

 extremity merely attenuatedly rounded. 



2. S. Cdmingii, Eanley, f. 3. — T. sp. praecedenti simillima, 

 sed autice multum longior, et tantum rotundato-attenuata ; radii 



