NUCULID*. 129 



concentric, rather depressed, usually absent above just behind the 

 subangular yet not much raised umbonal ridge. Extremity of 

 the somewhat shorter anterior side narrowed, bluntly rounded. 

 Posterior side gradually attenuated to an acuminated beak, the tip 

 subcentral, slightly upturned. Front dorsal slope somewhat convex, 

 not very decided : hinder dorsal slope moderate, straightish, even- 

 tually incurved. Ventral margin arched in front, straighter and 

 more rising behind, not conspicuously indented posteriorly. Lu- 

 nule narrow, inconspicuous : escutcheon large, angularly defined, 

 densely and most finely costellated lengthways, its lips protruding. 

 Under a powerful lens, some minute interstitial lyrse may at times 

 be descried both on the umboes and behind them. — D'Orbigny, 

 in his plate, has corrected the larger admeasurement (20 milli- 

 metres) he had indicated in his text. 



42. L. CiELATA, Hinds, f. 95, 96. — T. ovali-acuta (nonnun- 

 quam latior), postice rostrata, sequilateralis, ventricosa, cute oli- 

 vaceo-flavida nitidissima induta, undique, nisi postice superne, 

 concentrice sulcata. Extremitas rostri angularis, recurvata. Margo 

 dorsalis antice magis minusve declivis ; postice declivis, vel sub- 

 declivis, demum incurvatus ; ventralis utrinque acclivis, antice 

 arcuatus, in medio tantum couvexus. Arese dorsales sicut in L. 

 ventricosa, obsoletius autem insculptae. — Peaked-oval (or oboval), 

 more or less ventricose, retuse near the hinder slope, briefly yet 

 patulously gaping at the hinder tip, clothed with a lustrous yel- 

 lowish-olive epidermis, concentrically grooved, except on the dorsal 

 areas, and a smooth, narrow, triangular slip adjacent to the pos- 

 terior slope : umbonal ridge scarcely elevated. Sides subequal ; 

 the front, if either, the longer, rounded at its extremity ; posterior 

 side quickly beaked, its angular and upturned tip central. Front 

 dorsal edge more or less sloping and convex : hinder dorsal slope 

 more or less decided, incurved at its termination. Ventral margin 

 rising at both ends, arched in front, convex in the middle, nowhere 

 conspicuously retuse. Dorsal areas nearly like those of ventricosa, 

 but the sculpture somewhat obsolete.* — The shape (with its cor- 



* I am unable to procure an example of a Leda said to resemble this species, but 

 here condense the published description. — 



L. sulculata, Couth. — Thick, with a dark-olive skin, modified oval, rounded and 

 smooth at the anterior extremity, elsewhere with fine sharply incised concentric lines; 

 attenuated and subrostrated behind, the tip (which is more prominent above) some- 

 what obliquely truncated. Umbonal ridge blunt. Beaks protuberant, anterior. 

 Ventral edge curved. Lunule large, oval, profound, with mere wrinkles of increase. 

 Escutcheon ample, broadly elliptical, defined by an incised line, faintly striated. 

 Teeth 15-20. £-&-&■ 



The Lembulus sulrulaius of Ris9o is too inadequately defined for identification. 



vol.. in. i' 



