nuculida:. 127 



conspicue recurvata. Margo dorsalis antice vix declivis, postice 

 bis incurvatus; ventralis in medio maxime arcuatus, utrinque 

 multum acclivis. Area; dorsales baud insculplse; antica incon- 

 spicua ; postieaconcaviuscula, et sulco lato profundo circumscripta. 

 — Beaked-ovate, ventricose or tumid, only (yet much) gaping at 

 the hinder tip, of a polished ivory-white, with a very faint anterior 

 indented ray, closely grooved lengthways throughout; the sulci 

 shelving, except upon the beaks and near and upon the feebly 

 developed umbonal ridge, where they become broader and square- 

 cut, and their intervals form costellae. Anterior extremity rotun- 

 dately subangulated above, obliquely rounded below. Posterior 

 side attenuatedly beaked, its tip, which is contracted at its origin 

 both above and below, very narrow (yet blunt), peculiarly upturned 

 (in the adult), and above the middle. Front dorsal slope very 

 slight, straightish or plano-convex : hinder dorsal slope with a 

 double incurvation. Ventral margin much arcuated in the middle 

 and front, straighter behind, much rising at both ends, slightly 

 refuse near its posterior termination. Dorsal areas smooth or 

 nearly so : the front one inconspicuous ; the hinder one plano- 

 concave, environed by a deep, broad sulcus, which angulates its 

 sides, and makes it appear raised. — Under a powerful glass, a few 

 radiating lyrre may be descried near the commencement of the 

 indented ray : they are best seen in the younger individuals, which 

 are usually pale fulvous, and do not display the cocked-up beak, 

 being merely acuminated to a subcentral tip (Rec. Biv. pi. 19, f. 46). 

 39. L. puellata, Hinds, f. 94-. — T. perparva, subsequilateralis, 

 obovato-acuta, antice late rotundata, in medio tumida, postice 

 compressa et repente recurvato-acuminata ; alba, oculo armato 

 antice inclinato-sulcata, postice arctius sulco-costellata, radii im- 

 pressi expers, plica umbonali planulata, sed utrinque angulari, 

 munita. Margo dorsalis antice vix declivis, postice retusus de- 

 clivisque ; ventralis antice multum arcuatus, postice rectior et 

 multum acclivis. Area angulatim definita, duplex ; interior pla- 

 nulata, laevis, linea carinata circumscripta. Lunula inconspicua. 

 — Small, peaked-obovate, subequilateral, tumid in the middle, 

 compressed behind, white, devoid of a coloured epidermis or an 

 anterior indented ray ; smooth to the eye, but under the lens most 

 closely and finely (the dorsal areas excepted) sulcato-costellated ; 

 umbonal ridge planulate, subcarinately angular on either side. 

 Front extremity broadly rounded : hinder extremity abruptly 

 acuminated ; the tip upturned, rather above than below the middle. 

 Front dorsal slope slight, plano-convex. Hinder dorsal slope 

 moderate, refuse. Ventral margin much arcuated in the middle 



