ORTMANN: FAMILIES AND GENERA OF NAJADES., 269 
Color of soft parts of FE. beadleianus whitish; foot grayish; gills and 
palpi grayish-brown, as is also the mantle, except the margin, which is 
whitish, with the edge blackish posteriorly. 
Elliptio (?) spinosus (Lea). 
The anatomy has been described by Lea (Obs., X, 1863, p. 413). 
It is similar to that o! E. crassidens, but Lea mentions some peculiar- 
ities in the ovisacs, which I do not understand. The shell is of the 
crassidens-type, but its spines are unique and would possibly justify 
the erection of a separate genus: Canthyria Swainson, 1840. 
Elliptio complanatus (Dillwyn). 
Numerous specimens of this species, males, sterile and gravid 
females, have been investigated from the Delaware, Susquehanna, and 
Potomac drainages of eastern Pennsylvania and Maryland. The 
species is tachytictic, and the breeding season begins at the end of 
April, and lasts to the middle of June, possibly a little longer. 
The soft parts have been described by Lea (Obs., X, 1863, p. 
AID ye 
In the shell, this is a typical Elliptio, with the typical shape of this 
genus, and its typical beak-sculpture. In the soft parts, we find the 
edges of the mantle forming the usual openings. Anal and supra-anal 
are separated by a moderate mantle-connection, shorter than the anal, 
which has never been found missing. The branchial has large papille, 
while the anal has much finer ones. Posterior margins of palpi con- 
nected for a short distance. 
Gills corresponding to the shape of the shell, rather long and 
moderately wide, the inner rather wider. Diaphragm of the usual 
shape, inner lamina of inner gill free, except at anterior end. Septa 
and water-tubes well developed, the latter wide in the male. In the 
female only the outer gills are marsupial, and their septa are much 
crowded. When gravid, this gill swells only moderately, the edge 
remaining sharp, and the ovisacs assume a leaf-like shape, as also do 
the placente (figured by Lillie, 1895, pl. 1, fig. 1), which are not very 
solid when glochidia are present. The latter are always white, 
rather small, subovate, without hooks. They are longer than high. 
Length 0.20, height 0.19 mm. (see Plate XIX, fig. 1). 
Color of soft parts of the grayish white type, foot darker, also gills, 
the latter often suffused with black posteriorly. 
