ORTMANN: A MONOGRAPH OF THE NAJADES OF PENNSYLVANIA 330 
c!. Sculpture of the beak concentric, not heavy; supra-anal about as long as the united part of the 
margin of the mantle, which separates it from the anal opening. 
Genus Anodontoides Simpson. 
c*, Sculpture of the beak generally double-looped; supra-anal small, widely separated from the anal 
opening. Genus Anodonta Lamarck.” 
3. Subfamily Lampsritina Ortmann. 
Inner lamina of inner gills rarely more or less free from the abdominal sac, 
generally connected with it throughout; supra-anal opening separated from the 
anal, rarely entirely closed; branchial opening well defined; edge of the mantle 
in front of the branchial opening smooth to crenulated, or with peculiar papille 
or a flap; marsupium rarely formed by the whole outer gill, generally only by or 
within the posterior part of the outer gill; edge of marsupium, when charged, 
distending, and bulging out beyond the original edge of the gill, generally assuming 
a beaded appearance; water-tubes simple in the gravid female; glochidium semi- 
circular or semi-elliptic, without spine, rarely celt-shaped and with two spines; 
shell heavy or lighter, rounded, or oval, to elongate; color of epidermis rarely 
dull, mostly bright, with color markings; sculpture of the beak generally double- 
looped, but often obsolete, more rarely concentric; hinge generally complete, with 
well-developed teeth, which only in rare cases show a tendency to become reduced; 
sexual differences more or less noticeable in the shell, often very strongly expressed. 
GENERA 
@, Whole outer gill serving as marsupium, its edge thrown into a number of folds. 
Genus Ptychobranchus Simpson. 
a. Marsupium located in the posterior part of the outer gill, and projecting considerably beyond its original 
edge. 
b'. Inner edge of mantle in front of branchial opening smooth, crenulated, or with few and weak teeth, 
but without papille or flaps; male and female shell differing only slightly, or hardly at all. 
c!, Shell rounded, with surface sculpturings; marsupium consisting of comparatively few ovisacs, 
located near the centre of the outer gill. 
d@, A row of large knobs on each valve; marsupium projecting beyond the edge of the gill, not 
coiled up. Genus Obliquaria Rafinesque. | 
@. Sculpture of the surface nodular; marsupium projecting immensely beyond the edge of the 
gill, and coiled up spirally. Genus Cyprogenia Agassiz. 
c. Shell rounded, oval, or compressed, without surface sculpture; marsupium large, kidney-shaped, 
occupying a large portion of the posterior part of the outer gill. 
d'. Shell solid, rounded, ovate or triangular, more or less swollen; if compressed, not winged. 
*4Huropean writers (See Thiele in Brauer, Suesswasserfauna Deutschlands, Heft 19, 1909, p. 32) recently use Anodontites 
Bruguidre, 1792, for Anodonta Lamarck 1799. This is entirely wrong. The type of Anodontites is 
A. crispata Bruguiére a 
South American shell, belonging to Glabaris Gray 1847. Of course, Anodontites has the priority over Glabaris, and should be 
used in its place. 
