128 THE AMERICAN MIDLAND NATURALIST 
author sees fit to create a new genus for heros of Say:— 
\ 1.—An unusually heavv shell, with zigzag or V-shaped, 
sculpturing on upper part of disk and corrugate scupture 
on beaks. 
2.—A tendency of the inner laminae of the inner gills to 
become more or less united with the visceral mass. 
3.—The gravid marsupium an enormously distended pad, 
colored purplish, or slaty, with reddish splotches here and 
there parallel to the septa. 
4.—Thick, sole-shaped, suhsolid conglutinates with rusty- 
brown margins discharged more or less whole with glochi- 
dialying all through the conglutinated mass. 
5.—A large, vital glochidium with post-ventral margin ob- 
liquely rounded. 
6.—Breeding season intermediate, or tachytictic with late 
season (i. e., bearing glochidia in late winter but being 
sterile during the summer.) 
From Amblema this peculiar species must be removed on 
account of its beak sculpture which is more like that of Quadrula— 
especially of the ‘‘Lachrymosa”’ group, yet it is separated from 
the latter chiefly by its ponderous shell and rugose, V-shaped 
sculpturing on the umbonal region and upper part of disk. It 
has been grouped under Amblema more on account of the oblique 
folds on post-half of its shell; however, these plications are, after 
all, usually disposed differently with respect to the post-umbonal 
ridge and are not so constant and numerous, nor do they appear 
so early in the life history of the shell, as in the type for Amblema. 
The special reason that a new genus should be built for heros is 
on the basis of its unique character of soft parts. No other generic 
type of Unioninae (nor of any of the Naiades for that matter) 
possesses such peculiarities of form, color or size for its marsupium, 
conglutinate or glochidium; and as to its nutritive structures, 
none are so eccentric regarding the connection of the inner laminae 
to its inner gills. Its idiosynerasy of breeding habits would not 
only give it a special station, aside from all other Navades so far 
known, yet this physiological character may account for its oddity 
morphologically. The author has kept an accurate breeding 
record of heros throughout the year—especially for the 
winter months when other records have been incomplete—to_ 
find it gravid with ova of early embryos in fall and early winter, 
