ORTMANN: FAMILIES AND GENERA OF NAJADES. 247 
ing season lastsfrom the middle of May to the middle of July. The 
discharge of the glochidia has been observed on July 8, 1909. 
The soft parts have been described by Lea (Obs., X, 1863, p. 417), 
but incorrectly in several particulars. They also have been described 
by Simpson (in Baker, 1898, p. 82). 
Margin of the mantle drawn together by the gill-diaphragm, thus 
separating the anal and branchial openings. Anal and supra-anal 
separated by a very short mantle-connection, which is sometimes absent 
(torn?). Branchial opening with strong papille, anal also with papille, 
which, however, are much finer, and sometimes appear only as crenu- 
lations. Palpi of the usual shape, their posterior margins connected 
only at base or up to one-third of the length. 
Gills broad, the inner the wider, their anterior ends as usual. Dia- 
phragm normal, and inner lamina of the inner gills free from the ab- 
dominal sac, except at the anterior end. 
Gills with well-developed septa and water-tubes, as usual. In the 
female, marsupial structure is observed in all four gills, the septa being 
better developed, with folded epithelium, closer together, and the 
water-tubes being narrower. Yet in the outer gill the water-tubes are 
somewhat narrower than in the inner gill, which is chiefly noticeable 
at the base of the gills. In the gravid female, the gills swell moder- 
ately, so that the ovisacs assume a lanceolate, leaf-like shape, while the 
edges of the gills remain sharp and do not distend. Eggs whitish, 
filling the ovisacs in rather poorly connected masses, although a pla- 
centa-like cohesion is seen. But later on this placenta-structure is 
lost, and the glochidia are discharged in rather loose, irregular masses. 
Glochidia of suboval shape, without hooks. Length 0.21; height 
0.22 mm. (see Lea, Obs., VI, 1858, pl. 5, fig. 22, but not quite correct 
in shape; Ortmann, 1911), pl. 89, fig. 3). 
Color of soft parts whitish, foot, margin of mantle and gills pale 
brownish or yellowish. No trace of any brilliant colors (red or 
orange). 
Crenodonta perplicata (Conrad). 
One male, and two females, from Bayou Pierre, De Soto Parish, 
Louisiana, collected Aug. 6, 1910, have been received from L. S. Frier- 
son. One of the females proved to be gravid, and in the act of dis- 
charging glochidia. Three males, three females, and two young ones 
from Ouachita River, Arkadelphia, Arkansas, have been sent by H. E. 
Wheeler. 
