864 PROCEEDINGS OF THE NATIONAL MUSEUM. VOT..XX. 



Found in considerable numbers, at about forty-five stations, between 

 N". lat. 47 40', W. long. 47 35' 30", and N. lat. 35 12' 10", W. long. 74 

 57' !">", in 20i to 781 fathoms, 1872-1880. 



This species is more elongated and more regularly elliptical than any 

 of the allied species; the hinge-margin is also less angulated. 



A single specimen (No. 7 4325), station 43, off Cape Sable, in 90 fathoms, 

 1877, at first thought to be a distinct species, differs from the typical 

 form in being more oblong with the ventral margin less curved, the 

 posterior end more evenly rounded with only a slight indication of a 

 superior angulation, so that the shell has a pretty regular, narrow ellip- 

 tical form. In all other respects, however, it agrees well with the ordi- 

 nary form. This specimen, which receives the varietal name stricta, 

 is figured on Plate LXXX, fig. 1. 



Length, 5 mm.; height, 3 mm.; breadth, 1.3 mm.; length from beak 

 to posterior end, 3 mm. 



YOLDIELLA INFLATA Verrill and Bush. 

 (Plates LXXX. fig. 8; LXXXII, figs. 5, 6.) 



Yoldia liii'ida VERRILL, Trans. Conn. Acad., VI, p. 279, 1884 (in part). 

 Yoldiella inflata VERUILL and BUSH, Amer. Journ. Sci., Ill, p. 56, figs. 3, 4, 11, 

 January, 1897. 



Shell small, swollen, rather short, subovate, with the posterior end 

 broad, angulated postero-dorsally ; beaks at about the anterior third; 

 surface smooth. An tero- dorsal margin regularly convex and sloping 

 rapidly to the anterior end which is evenly rounded, very obtuse, and 

 passes insensibly into the evenly curved ventral margin which is 

 decidedly convex, although the degree of convexity varies considerably 

 in different specimens; the posterior end is obliquely subtruncated, 

 with an obtuse curve below and an obtusely rounded angle at its upper 

 extremity where it joins the nearly straight postero-dorsal margin. 

 The umbos are full and well-rounded but not very prominent; the 

 beaks are small, directly incurved, appressed to the margin. There is 

 no distinct lunule but the margin is slightly pinched up in a small crest 

 both before and behind the beaks. The ligament is delicate and shows 

 slightly on both sides of the beak. Epidermis pale olive yellow or straw 

 color; surface smooth, shining, reflecting prismatic colors, showing 

 more or less distinct lines of growth which sometimes become regular, 

 concentric, very fine striations, especially anteriorly. Hinge-margin 

 well developed, moderately broad and considerably thickened, forming 

 an obtuse angle at the beak where it is thin, encroached upon by the 

 beak and interrupted by the cartilage-pit; the two portions are nearly 

 equal in length, the anterior somewhat arched, the posterior nearly 

 straight, each having a thin, smooth border above the teeth, about 

 equal in breadth to the hinge-plate. In the largest specimens there 

 are nine to eleven (most frequently ten) rather stout, angular teeth and 

 about ten very similar posterior ones; the cartilage-pit is small and 



