ORTMANN: FAMILIES AND GENERA OF NAJADES. 343 
Eurynia (Eurynia) nasuta (Say). 
Numerous specimens have been investigated, partly from Lake 
Erie, partly from the Delaware drainage in eastern Pennsylvania and 
New Jersey. 
According to Conner (1907, p. 88) this species breeds all the year 
round, that is to say, the end of one breeding season overlaps the 
beginning of the next in midsummer. This refers to the Delaware 
drainage in eastern Pennsylvania. For this region I have only a few 
observations (in the months of September and May). From Lake 
Erie I have specimens with eggs collected at the end of August (be- 
ginning the breeding season), and others with glochidia collected in 
May, June, and as late as July 7. On the latter date specimens in 
the act of discharging were observed. But there is surely an ‘‘in- 
terim’’ in Lake Erie, at least in July, for of all the specimens collected 
on July 8, 12, 22, and 23, not a single one was gravid, although numer- 
ous sterile females were among them. 
The soft parts have been described by Lea (Obs., X, 1863, p. 403), 
but in error the marsupium is said to occupy the whole length of the 
gill. The papille of the edge of the mantle have been described by 
Ortmann (19110, p. 317). 
The inner edge of the mantle of the female has in front of the 
branchial a rather regular row of numerous (as many as thirty and 
more) rather closely set, subequal papilla, which are rather small, 
subconical, and run forward to almost the middle of the ventral margin, 
where they disappear gradually and pass into the smooth anterior 
part of the edge. This row is not accompanied by a distinct black 
band, but there is brownish pigment in this region. Marsupium 
formed by over half (up to three-fourths) of the outer gills, with a very 
small non-marsupial section behind. Ovisacs fifteen to forty, their 
ends having no black pigment. Glochidia (Lea, Obs., XIII, 1874, 
pl. 21, fig. 2), similar in shape to those of the preceding species, rather 
large. Length 0.25; height 0.29 mm. (see Plate XX, fig. 8). 
Mantle-connection between anal and supra-anal rather long, 
longer than the anal. Inner lamina of the inner gills connected with 
the abdominal sac, often with a small hole at the posterior end of the 
foot. Posterior margins of palpi connected only at base. 
