NUCULID^. 



the ordinary site of an umbonal ridge not elevated, but convex 

 and smooth, elsewhere regularly and concentrically sculjjturcd, by 

 broad imbricated flattened folds before the indentation, by twice 

 as numerous close shelving stris behind it. Front side much the 

 shorter, unsymmetrically rounded at the extremity. Hinder side 

 rapidly contracted by the incurvation, behind the beaks, of both 

 upper and lower edges, then gradually acuminated to a bluntly 

 oblique extremity, the tip being more prominent dorsally. Front 

 dorsal edge scarcely sloping, plano-convex ; hinder dorsal slope 

 rather slight, much produced, plano-retuse. Ventral margin 

 arcuated in froTit, rising, after the central refusion, with little 

 convexity. Escutcheon carinately defined, rather broad. Lunule 

 just perceptible. Cartilage-pit small, triangular. Teeth numerous, 

 particularly behind. — The epidermis is of a yellowish ash-colour. 



6. L. ELECTA, A. Adams, f. 40, 41. — T. auguste lanceolato- 

 rostrata, utrinque attenuata, requilateralis, nivea, compressa, un- 

 dique longitudinaliter striolata : striolse auticse minus conspicuai ; 

 postica; arctiores, magisque obliquae. Extremitas postica oblique 

 subtruncata. Marge dorsalis posticus incurvatus, vix declivis ; 

 ventralis in medio arcuatus. Area impressa, erenato-marginata. 

 — Elongated, beaked-lanceolate, thin, compressed, shining white, 

 everywhere minutely yet distinctly sculptured : shelvingly scratched 

 lengthways by fine strife, which in front (where they are crossed 

 by the wrinkles of growth) are more distant and less manifest, 

 and become closer and more slanting posteriorly ; the scarcely 

 raised extreme posterior ridge is smooth to the eye, yet is barred 

 with raised concentric wrinkles. Sides equal or very nearly so ; 

 the anterior one gradually tapering to a narrow rounded tip ; the 

 posterior one beaked and still more attenuated, the extreme tip 

 obliquely subtruneated and angulated above. Front dorsal slope 

 moderate, convex ; hinder dorsal slope, slight, incurved. A'^entral 

 margin arched in the middle, rising at both ends, barely subretuse 

 in front. Beaks minute, sharp, perceptibly projecting. Escutcheon 

 sunken, crenately margined. Lunule perceptible. 



7. L. Tayloui, Ilaiilcy, f. 35. — T. elongata, antice aliquantum 

 brevior et rotundato-lanceolata, postice atteimata et subrostrata ; 

 nivea, subcompressa, densius longitudinaliter striata : stria; antice 

 concentriciB et eievatce, mox acclinatse et (certissime in valvula 

 sinistra ubi inferne prope plicam umbonalem planulatam demumque 

 sublsevigatam prorsus desuut) magis minusve obliquae. Margo 

 dorsalis uterque vix declivis. Area planulata, crenulato-margi- 

 nata. — Elongated, rather shorter and rounded-lanceolate in front. 



