348 Annals of the Carnegie Museum. 



anodontoides (my specimens from Texas are typical and undoubted 

 anodontoides), and it is not at all "horny," and corresponds to the 

 flap described above. 



Lampsilis luteola (Lamarck). 



Many specimens from the Lake Erie and Ohio drainages in western 

 Pennsylvania, and also from Kansas and Arkansas, have been in- 

 vestigated. 



Bradytictic, and may be found gravid practically all the year round. 

 The breeding season begins at the beginning of August, and ends in 

 July, and may overlap with the next toward the end of July. But in 

 July there is an indication of an interim, gravid specimens being quite 

 rare. In the Ohio drainage, the females have generally discharged 

 their glochidia by the beginning of July, and only single belated in- 

 dividuals are met with later. In Lake Erie, discharging females were 

 found more frequently in July, as late as July 12. No gravid females 

 have ever been found between July 12 and August 4 by myself. 



The soft parts have been described by Lea (Obs., X, 1863, p. 402) 

 and Simpson (in Baker, 1898, p. 104). 



Mantle-connection between anal and supra-anal of medium length, 

 shorter than anal. Anal crenulated, branchial with papillae. In 

 front of branchial the female has on the inner edge of the mantle a 

 typically developed flap (see Ortmann, 191 lb, p. 321). It has the 

 shape of a ribbon-like keel, with irregular, rather distant teeth, but 

 no papillae, 53 and its anterior end projects considerably, even when 

 contracted, and has great powers of expansion. The marginal teeth 

 are largest at the free lobe, which appears lacerated. There are a 

 number of irregular teeth on the edge of the mantle in front of the 

 lobe, but soon the edge becomes smooth. On the inner side of the 

 flap there is a broad streak of black pigment. Eye-spot (in alcoholic 

 material) indistinct. The flap extends over about one-third of the 

 lower margin. 



Posterior margins of palpi connected for about one-fourth of their 

 length. Gills and diaphragm normal. Inner lamina of inner gills 

 entirely connected, rarely a very small hole remaining at the posterior 

 end of the foot. 



Marsupium kidney-shaped, occupying about the posterior half of 



63 when strongly contracted by the action of alcohol, the teeth become thicker, 

 and appear like papilla?, but when expanded, they are flat (not sub-cylindrical). 



