THE NAUTILUS. 125 
Long. 274, alt. 2°0, diam. 1:4 mill., (long. 2-3 mill.) ; young, as 
contained in parent, 0°8 mill. long. 
Habitat: Region of the Great Lakes, in deep water—Lake 
Michigan: Racine, Wis., dredged (Mr. Geo. T. Marston) ; different 
places on the Michigan side, partly from a depth of 24 meters; Pine 
Lake, Mich., dredged ; Green Lake, Wis., dredged ; from stomachs 
of White Fish, Lake Michigan, all sent by Mr. Bryant Walker, in 
1894, and partly since. They were believed be a new form, but 
publication was deferred. 
In March, 1895, Mr. Geo. T. Marston sent me two lots from 
dredgings, writing: “No. A. 208, Pis. abyssorum Stimpson, were 
from Dr. P. R. Hoy, Racine, Wis. He wrote me that they were 
first found in the stomachs of \White Fish taken in Lake Michigan, 
near Racine, Wis., in 1870, by a party of gentlemen including Wm. 
Stimpson and himself. The party were investigating the food of 
White Fish, then unknown. I quote from Hoy’s letter: ‘ In 1870 
we dragged in Lake Michigav—Wm. Stimpson assisted—we got 
several of the Pisidium and three species of Crustaceans, all of which 
were new. Stimpson described the several new species—the names 
were published—I do not recollect where published—but the descrip- 
tion was written out with the greatest care and were to be published 
in the Proc. of the Chicago Acad. Se, of which Stimpson was 
secretary at the time. All were burnt at the time of the great 
fire’ Mr. Marston subsequently had correspondence with several 
conchologists, but the matter remained unsettled. The two lots 
contained different forms of small Pisidia mixed up; but the most 
numerous and most conspicuous specimens represented the form now 
described under Stimpson’s name. There js no absolute certainty 
that this is the same Pisidium the author had described, but it is 
the nearest in probability, and so to-day by the efforts of Mr. Mars- 
ton, we can do justice to the deceased scientist. For the above de- 
scription the writer is wholly responsible. The name (only) Pis. 
abyssorum has been published by Smith in his “Sketch of the In- 
vertebrate Fauna of Lake Superior,” according to a kind communi- 
cation of Mr. Bryant Walker. 
The form comes nearest Pis. splendidulwm, in size and shape; but 
it is less inflated, the beaks are less prominent, the color is much 
paler (whitish), the shell thinner, and the hinge much finer and, as 
mentioned, partly defective. 
Pis. pauperculum var. Nylanderi n. 
Different from the type in the following points ; it is comparatively 
