Ortmann; Families vnd Genera ok Najades. 283 



of marsupium). A figure of the gravid female has been published by 

 Lefevre and Curtis (1910, pi. 1, fig. 6), but the essential structu 

 the marsupium is not brought out. 



Mantle-connection between anal and supra-anal about as long as 

 the anal, supra-anal slightly longer. In other respects, the soft 

 parts are essentially identical with those of the other species of the 

 genus. Glochidia ^\ similar size, but shape more distinctly tri- 

 angular, not so long in comparison with height. Length and height 

 0.34 mm. (see Lea, Obs., VI, 1858, pi. 5, fig. 29, and Lefevre and Curtis, 

 /. c, p. 97, fig. A. The measurements given by Lefevre and Curtis, 

 0.29 X 0.30, are at variance with mine; see also Ortmann, 191 lb, 

 pi. 89, fig. 11). 



Color whitish when young, but foot and gills browner when old. 



Abdominal sac brown-orange, marsupium pale yellow to brown. 



Symphynota costata (Rafinesque). 



Many specimens from western Pennsylvania have been investigated, 

 and two gravid females from Hurricane Creek, Gurley, Madison Co., 

 Alabama (H. E. Wheeler, Sept. 13, 1910). 



Breeding season from August to May. Eggs were found only in 

 August and September. 



Soft parts described by Lea (as Margaritana rugosa, Obs., X, 1863, 

 p. 446) and Simpson (in Baker, 1898, p. 58). 



Soft parts like those of S. compressa. It is noteworthy that the 

 anal is very large, and the mantle-connection between anal and supra- 

 anal comparatively short, much shorter than the anal. Glochidia 

 (see Lea, Obs., VI, 1858, pi. 5, fig. 26; Lefevre and Curtis, 1910, p. 97, 

 fig. B, length 0.35; height 0.39), larger, more distinctly triangular, 

 higher than long. Length 0.34; height 0.37 mm. 



This species is remarkable on account of its beak-sculpture, which 

 does not conform to the double-looped type characteristic of this 

 genus. In S. costata, the later bars (toward the disk) are rather heavy 

 and straight, with hardly an indication of a sinuation. The earliest 

 bars are concentric as usual. But between the earliest and the latest, 

 are some bars, which show an indication of sinuation more or less 

 well-developed. 



This condition shows that we must not lay too much stress upon 

 beak-sculpture as a general systematic character. 5. costata is un- 



