NO. 1139. DEEP-WATER MOLLUSCAVERRILL AND BUSH. 857 



LEDELLA PARVA Verrill and Bush. 



( Plate LXXXI, tig. 1.) 



Ledclla parva VEIUULL :iinl Brsn, Anier. Journ. Sci., Ill, p. 51, fig. 18, January, 

 1897. 



Shell minute, narrow-ovate, the anterior end the longer and obtusely 

 rounded, and the posterior end with a short, subtruncate, median ros- 

 trum. Umbos somewhat swollen; beaks a little prominent and turned 

 slightly backward. The surface is nearly smooth, showing only micro- 

 scopic lines of growth. The autero-dorsal margin is elongated, slightly 

 convex, and slopes very gradually to the rounded anterior end 5 the 

 ventral margin is broadly and evenly convex, but somewhat pinched up 

 posteriorly to form a slight emargination below the rostrum, which is 

 short, narrow, subtruncate at the tip, and is defined by a slight, incon- 

 spicuous ridge; the postero-dorsal margin is nearly straight and slopes 

 rapidly to the upper angle of the rostrum. The hinge plate is strong, 

 considerably thickened, with a very obtuse angle at the beak; the ante- 

 rior portion is the longer with the inner margin convex, and the posterior 

 portion is the wider, more oblique, with the inner margin strongly con- 

 cave; the plain outer margin is sharp and projects considerably above 

 the teeth which are strong, stand nearly erect, and are less V-shaped 

 than usual. There are about fifteen in the anterior series, of which 

 three or four proximal ones are quite small, and nine stouter ones in the 

 posterior series, including one very small one next the beak. Thechon- 

 drophore is rather small and deep with a distinctly projecting inner 

 edge. 



Length, 3 mm.; height, 2 mm. 



One valve (No. 78365), station 2089, off Marthas Vineyard, in 525 

 fathoms, 1886. 



This species seems to be closely allied to L. semen (Smith) from off 

 the coast of Brazil (Voyage of the Challenger), but that species, although 

 of the same size, has fewer teeth, nine of which are said be anterior and 

 twelve posterior. 



PORTLANDIA Morch, 1857. 

 Portlantlia VKKRILL and BUSH, Anier. Journ. Sci., Ill, pp. HI, 62, January, 1S!7. 



Type. Portlandia arctica(Gray) 1819 == Leda portlandica (Hitchcock). 



We consider this a distinct genus, but would restrict it to the orig- 

 inal type, unless a few species, which we have not seen, should prove to 

 belong to it. In any case it does not appear that any of the northern 

 species of Europe and America that have been referred to it are really 

 closely allied to the type. In many respects this genus is intermediate 

 between Leda and Yoldia. In its closed shell, definite rostrum, etc., 

 it agrees more nearly with the former, but in general outline, with the 

 latter. 



