ORTMANN: FAMILIES AND GENERA OF NAJADES. 289 
but septa more irregular in the non-marsupial gills. In the marsupial 
gill of the female, the septa are crowded, even more so than in A. 
cygnea. The tissue of the gills is generally more delicate in A. com- 
planata, but the various elements are similar to those of A. cygnea. 
The glochidia (see Plate XIX, fig. 3, also Schierholz, 1889, pl. 2, fig. 29; 
Fleming, 1875, pl. 3, fig. 11) are smaller, longer than high, with shorter 
hooks; thus the outline is less distinctly triangular, and less pointed. 
I find the length to be 0.34, the height 0.32; while Haas (1910a) gives 
0.33 mm., but does not say in which dimension. 
For this species, Bourguignat (1880, pp. 11-13) has created the 
genus Pseudanodonta, founded originally upon the shape of the shell 
and differences in the hinge. The first character is quite pronounced, 
but cannot be regarded under any condition as a generic character; 
the second does not exist at all, which is best shown by the fact that 
it has been dropped entirely by subsequent authors (Haas). Other 
writers have added to the distinctive characters, which have been 
condensed by Haas (191t0a, p. 110; and 
1910c, p. 170). According to Germain, the 
beak-sculpture is said to be different. 
Pseudanodonta is reported to have three to 
five tubercular ridges, which are absent in 
the true Anodonta, while in Anodonta, there 
ll) 
are flexuous ridges, but never tubercular 
ridges (“‘les Pseudanodontes ont . . . trois 
ll 
4) 
mp 
| 
) 
) 
a cing rides tuberculeuses . . . qui man- 
quent chez les véritables Anodontes. Chez ——] 
oe ——) 
les Anodontes, les sommets sont parfois i —/ 
ornés de rides flexueuses, mais jamais de 
rides tuberculeuses’’). This statement isan 
intentional exaggeration of the actual con- 
wy : Fic. 14a. Left gills of a 
ditions, worded with the purpose to obscure 
sterile female from same lo- 
the similarities, and to emphasize the differ-  cality. 
ences. The fact is that in both Anodonta 
and Pseudanodonta, the beak-sculpture is of the same type, and 
consists of a number of double-looped bars, of which, in complanata, 
the posterior loop is slightly more swollen, but not tubercular. Haas 
also described the beak-sculpture of Pseudanodonta as ‘‘ consisting of 
a few isolated, rather elevated tubercles,’’ which is positively wrong, 
as is shown by the specimens before me. 
