126 BULLETIN OF THE 



rounded, especially the posterior end ; in ccelata the lunular areas are denned 

 by deep grooves or ridges and dissimilar sculpture, in corpulenta they are so 

 faintly defined as to be nearly invisible ; corpulenta has about fifteen teeth on 

 each side of the beak, which is not inclined ; in cozlata there are about fifteen 

 posterior and twenty anterior teeth, and the beak is posteriorly inclined ; the 

 ligament in the latter is wholly internal, in corpulenta it extends equally on 

 each side of the beak external to the dorsal margin, is about 2.0 mm. long, 

 black, and when weathered away in detached valves exhibits a flattened area 

 beneath each beak with a little pit in the centre, which last usually retains a 

 particle of ligament, simulating an internal ligament. Shell with a light olive 

 polished epidermis, porcellanous, extremely inflated, the young proportionately 

 longer and less rounded. Lon. 9.5 ; alt. 6.0 ; diam. 5.0 mm. 



Station 23, 190 fms. ; Station 21, 287 fms. ; Station 47, 331 fms. ; Sigsbee, 

 off Havana, 450 fms. 



Some things seem to indicate that the young have the cartilage wholl)- in- 

 ternal, but this is not certain, as the apparent young may belong to a different 

 species. Except the difference of the ligament, however, there seem to be no 

 differential characters between them. 



This species does not gape at all. The epidermis is polished. The ligament 

 is central, not at one side of the beaks as in Solenella and the typical Neilo. 

 The latter, as hitherto defined, will not admit it, nor will typical Leda. I re- 

 gard it as one of the links which knit together the assemblage of the NucvMda 

 in a network of ramifying relationships. Should it be thought worthy of a 

 name it may be called Neilonella, and it is certainly far more distinguishable 

 than many groups which have been named and segregated by Bellardi and 

 others. 



Leda vitrea (?) D'Orbigny, var. cerata. 

 L. vitrea D'Orbigny, Sagra, Moll. Cuba, II. p. 262, PI. XXVI. figs. 27-29 (1846). 



Barbados, 100 fms.; Sigsbee, off Havana, 450 fms. 



I am not sure that these shells should be referred to D'Orbigny's species. 

 They are more obtuse at the posterior end ; the sculpture is strong only over 

 the basal middle part, elsewhere it and the carinae about the lunule and es- 

 cutcheon are obsolete. It may take the varietal name of cerata (from its pecu- 

 liar whitish lustre) for the present, or until more material can be examined, or 

 a comparison made with typical specimens of D'Orbigny's species. The gen- 

 eral features, except those above noted, are very similar to those of the shell he 

 figures, and these specimens reach a length of 6.5 mm. 



Leda solida n. s. 



Shell almost equilateral, with the beaks inclined a little backward, stout, 

 solid, smooth, except l<>r rathex well-marked lines of growth ; anterior end 



broadly rounded ; posterior end more pointed, but not carinuted, sulcated, nor 



