A. E. Verrill — Catalogue of Marine Mollusca. 
531 
I have myself examined Mr. Dali’s series, which show considerable 
variation, indicating that his view is likely to prove correct. But 
none of his specimens agree very closely with mine. 
Stations 869 and 871, 115 to 192 fathoms ; 949, 100 fathoms. Six 
specimens obtained. Gulf of Mexico, 287 to 2,805 fathoms, — Blake 
Expedition (t. Dali). Off St. Thomas, W. I., 390 fathoms, — Chal- 
lenger Expedition (t. Watson). 
Mach ceroplax obscura , var. bella (Verkr.). 
Margarita bella Yerkruzen, Jahrb. d. Mall. Gesellsch.. 1875. 
Machceroplax bella Friele, Arehiv. for Math. Xaturv., 1876. p. 314. 
G. 0. Sars. op. cit., p. 137, pi. 9, figs. 5 a-c. 
Verrill. Proc. U. S. Xat. Mus., iii, 1878 (description). 
This Appears to be only a highly sculptured variety of M. obscura , 
but it seems to be identical with the form figured by G. O. Sars. It 
differs from the typical form chiefly iu having the base covered with 
distinct, incised, spiral lines. In some specimens the curved radiating 
ribs or undulations on the base are well-marked, as in the typical 
form, in others they are more or less obsolete. The presence of a 
slight spiral carina, or angle, bordering the umbilicus, is variable in 
both forms, being, in some specimens, pretty well-marked, in others 
entirely absent. The sculpture on the upper whorls is also variable 
in both varieties. The transverse ribs are usually rather more evident 
in var. bella , but they are often equally evident in typical obscura , 
frequently they are almost obsolete, except on the earlier whorls. 
The height of the spire varies greatly in both varieties. 
Variety bella is the predominant form at Eastport, Me., aud in the 
Bay of Fundy, where I dredged it in 1864, 1865, 1868, 1870, in 10 to 
40 fathoms. Gulf of Maine, 67 to 86 fathoms, 1874; George’s Bank, 
43 to 45 fathoms, 1872 ; oft Cape Cod, 1879. — U. S. Fish Com. 
Var. planula , nov. 
Another form of M. obscura frequently occurs south of Cape Cod, 
in 15 to 30 fathoms. In this the base is nearly smooth, with the 
radiating ribs obsolete, or indicated merely by bands of brownish 
color, while the spiral lines are entirely wanting, or occur only near 
the periphery, and often in the umbilicus, which may or may not be 
defined by an angular border. The bodv-whorl usually has three or 
four, more or less distinct, but low, angular, spiral cinguli, of which 
the first, just below the suture, usually forms only a slight ridge on 
the flattened subsutural band, and is often entirely absent ; the sec- 
Tbans. Conn. Acad., Vol. V. 64 July, 1882. 
