844 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL.XX 



This .species is allied to 71. f/lomcrula Ball. The latter differs in hav 

 ing a, less rounded form with a longer hinge-margin, more definite 

 terminal angles, and much more numerous and smaller teeth which are 

 nearly continuous. In our specimens of B. ylomerula of corresponding 

 size, there are about ten teeth in each series and they are about one-half 

 as large. According to Mr. Dall's figures, the umbos of his species are 

 larger than in the more northern form, but our specimens of his species 

 have the umbos smaller than is indicated by his figures. The position 

 of the beaks and form of the ligamental area is nearly the same in both 

 species; but the latter appears to be a little wider in ours and the 

 beaks are a trifle more oblique. The external sculpture is similar but 

 the radial lines are decidedly stronger and less numerous in glomerula, 

 and the sculpture is quite different in the two valves, while in ours 

 there is no perceptible difference. B. inwquiscnlpta (Smith) is also a 

 closely allied species which Mr. Dall considers identical with B. glome- 

 rula. Mr. Smith's figures are quite different from those of Mr. Dall, 

 and also from our West Indian specimens of the latter, and still more 

 different from B. dbyssorum. 



BATHYARCA PROFUNDICOLA (Verrill). 



(Plate LXXVIII, fig. 2.) 



Area profundicola VERRILL, Trans. Coim. Acacl., VI, p. 439, pi. XLIV, figs. 23, 

 23a, 1885. DALL, Bull. Mus. Comp. Zool., XII, p. 245, 1886. 



Macrodon profundicola DALL, Bull. U. S. Nat. Mus., No. 37, p. 42, pi. XLVI, figs. 23, 

 23a, 1889. 



A very few specimens, at three stations, between N. lat. 40 29', W. 

 long. OGo 4', and N. lat. .'57, W. long. 71 54', in 1,769 to 2,020 fathoms, 

 1884 and 1885. Also among Foramiuifera, station 2385, N. lat. 28 51', 

 W. long. 88 18', in 730 fathoms. 



BATHYARCA ANOMALA, new species. 

 (Plate LXXVII, fig. 8.) 



Shell small, oblong, inequilateral, much swollen with large prominent 

 umbos, and pointed beaks, curved strongly forward and considerably 

 separated, owing to the unusually wide, lanceolate, ligameutal area, 

 which is covered behind the beaks with the remains of a dark thick- 

 ened ligament. Dorsal margin straight for nearly its entire length; 

 anterior and posterior ends broadly and about equally rounded, the 

 posterior a little the more swollen below and longer; ventral margin 

 broadly rounded, a little prominent in the middle, with a slight byssal 

 indentation in front. Surface everywhere covered with fine, regular, 

 raised, radiating lines which are decussated by finer lines of growth; 

 the rather thin brown epidermis is scaly or chaffy on the radii, espe- 

 cially toward the margins, where it forms minute points. Hinge-margin 

 considerably thickened, increasing in strength toward the ends; in the 



