142 NUOULIDvTS. 



64. L. Eightsii, Couthouy, f. 164. — T. convexa, ovalis, postice 

 brevior et abbreviato-subrostrata, concentrice plicato-corrugata, 

 cute valida olivaceo-nigrescente induta. Extrernitas postica sub- 

 oblique obtusa. Margo dorsalis posticus declivis, subretusus. 

 Area baud definita, externe subconcava. Lunula plauulata. Dentes 

 pauci. — Oval, merely convex, gaping at both ends, much so pos- 

 teriorly, less so (and ventrally) in front, covered by a shining 

 blackish-olive strong cuticle, concentrically marked by rather 

 distant depressed, yet very manifest, pliciform wrinkles. Anterior 

 side occupying about four-sevenths of the total length ; its upper 

 and lower slopes, the former of which is decided and subarcuated, 

 the latter much rising, almost symmetrical; its tip (in the adult) 

 narrower and less rounded than the broad extremity of the slightly 

 beaked hinder side. Posterior dorsal slope decided, eventually 

 refuse. Ventral margin everywhere arcuated, not distinctly refuse 

 posteriorly. Front dorsal area flattened, manifest. Lips of the 

 escutcheon, which is not sharply defined, but gradually concave 

 at the circumference, pouting. Interior bluish-white. Only about 

 seven teeth on either side of the cartilage-pit, which is very large, 

 and with a rounded base. — In the only adult example known to 

 me (belonging to Mr. Metcalfe) there is present in one of the 

 valves, towards the lower margin, a pencil of regular closely dis- 

 posed radiating strise, and in the other of interrupted grain-like 

 lines. A perceptible, yet almost obsolete, broad shallow indented 

 ray is manifest in both valves.* Although stated by Jay to have 

 been published in the ' Annals of the Lyceum/ no description of 

 it is to be met with in that work. 



65. L. japonica, A. Adams, f. 14. — T. subovalis, postice bre- 

 vior et abbreviato-subcuneiformis, lasvis, subventricosa, cute polita 

 cinereo-virescente vel pallide olivaceo-flava induta. Margines dor- 

 sales vix declives ; anticus subrectus ; posticus produetus, incur- 

 vatus. Margo ventralis in medio subretusus, utrinque convexus 

 et valde acclivis. Umbones latiusculi, baud multum eminentes. 

 Area angustissima, vix retusa, acute definita. Dentes utrinque 



parum conspicua ; dentibus anticis 10, posticis 12, parvis. 0'22- 0'12." Massa- 

 chusetts Bay, in deep water. Narrower and more inflated than the young of Tlira- 

 ciaformis. 



* I am unable to identify the N. limosa of Philippi (Zeitschr. Malakoz. 1845, p. 

 75), whose shape must have approached this species. " Testa magna, ovato-oblonga, 

 subelliptica, subsequilatera, compressa, kevi, epidermide castanea tecta ; fovea liga- 

 mentali maxima, transversa, triangulari. Sinus Hudsou." We are informed in 

 addition that the description was drawn up from a single valve of Xoldia, that the 

 dorsal arch was greater than the ventral one, the cartilage-pit was very large aud 

 prominent, and that there were from seventeen to twenty teeth ou one side. 



