ORTMANN: FAMILIES AND GENERA OF NAJADES. Bal 
mens) either merely suddenly truncated in front, or forms a small 
free lobe, variable in my more or less contracted specimens. Along 
its edge this expansion is crenulated, but has no papille, and the whole 
inner side of this flap is of a brownish black color, sometimes a distinctly 
brown streak between two black streaks is seen. Noeye-spot has been 
observed. The flap extends over about one-third of the lower margin, 
and farther in front the inner edge of the mantle is smooth. 
Posterior margins of palpi connected for about one-fourth of their 
length. Gills and diaphragm of usual shape and structure. Inner 
lamina of inner gills connected with abdominal sac. 
Marsupium kidney-shaped, occupying about the posterior half of 
the outer gill, composed of numerous (about thirty) ovisacs. Margin 
of marsupium with blackish pigment. A very small section of the 
gill posteriorly is non-marsupial. Glochidia (Lea, Obs., VI, 1858, 
pl. 5, fig. 2) rather large, subovate. Length 0.20; height 0.26 mm. 
(see Plate XX, fig. 9). 
Color of soft parts whitish, with little brown on the edge of the 
mantle, and the markings on the flap and the marsupium as described 
above. 
According to the shape of the shell, this species was always sup- 
posed to be closely related to Eurynia recta, but I doubt whether there 
is actually a close relationship between these two species. The 
mantle-flap of L. anodontoides is entirely different from the papille 
of FE. recta. However, in L. anodontoides the mantle-flap has not yet 
attained the typical development of the genus, and the anterior free 
end is in particular rather indistinct. Probably it is the most primi- 
tive form of Lampsilis and connects this genus with more Eurynia- 
like ancestors, but it cannot be placed in Eurynia on account of the 
lack of papillae on the edge of the mantle. 
Lampsilis fallaciosa Smith. 
I have not seen the soft parts of this form, but I doubt very much 
whether it is specifically distinct from L. anodontoides. Among my 
specimens from Kansas River, there are some, to which this name might 
be applied. Among other material likewise in the Carnegie Museum 
I cannot sharply distinguish these two forms. 
Simpson (1900a, p. 75) says: “in L. fallaciosa there is a horny, 
brown, raised streak on the inside of the mantle behind, that I do not 
find in anodontoides.”’ This ‘‘streak,’’ however, is also present in 
