ORTMANN: FAMILIES AND GENERA OF NAJADES. 353 
hanna at York Haven, while on August 14, at Selinsgrove, they were 
frequent, but had only eggs. Conner’s notes (1909, p. I12) are 
unreliable, for he has confounded this species with L. ochracea, as I 
discovered from specimens he sent to me. He gives for ochracea 
(which would be this species) that it is gravid in April, May, and June. 
My observations are incomplete, but there seems to be an interim at 
least at the beginning of August. Perhaps the conditions are similar 
to those in the allied species. 
Lea’s figure (Obs., II, 1838, pl. 15, fig. 45) of the soft parts is entirely 
useless, but the soft parts agree fully with the preceding species. 
The color is much like L. ventricosa, but the margin of the mantle and 
inner side of the flap are generally of a beautiful chestnut tint. Black 
line on flap sometimes wanting. 
I have only one specimen with glochidia, and even in this they are 
too young to be correctly measured. But they seem to have the gen- 
eral shape and size of those of the foregoing species. 
Lampsilis orbiculata (Hildreth). 
Three females, two of them gravid, from the Ohio River in Beaver 
Co., Pennsylvania, have been examined. 
This species was found gravid with eggs in August (10 and 24), and 
with glochidia in September, and thus the beginning of the season 
agrees with that of the other species of this genus. 
Although this species is placed by Simpson close to L. ligamentina, 
it is not at all related to the latter, which is a Nephronajas, while this 
is a true Lampsilis, as is shown by the presence of a typical flap (Ort- 
mann, 19110, p. 321). This flap has numerous teeth along its edge, 
and projects at the anterior end in a free lobe. It also has black 
pigment on the inside. An eye-spot has not been seen, but this may 
be obscured on account of the contracted condition of my specimens. 
All the rest of the soft parts are like those of the foregoing species. 
The glochidia (Ortmann, 19110, pl. 89, fig. 22) are peculiar in so far 
that I have on my slides two sizes of them. The smaller is more fre- 
quent, length 0.19; height 0.21 mm., and among them are rather rarely 
larger ones, length 0.20; height 0.25 mm. No intergrades seem to be 
present. Itis not entirely impossible that by some accident in making 
the slide, the glochidia of another species have become mixed with 
this one, but this is not very likely. There are no glochidia having 
the dimensions of the larger ones, except those of L. anodontoides. 
