Ortmann; Families \\i> Genera of Najadi . 24] 



anal, l)iit mantle-connection between them ver;j short, and deciduous, 

 often absent. Inner lamina of inner gills free from abdominal sac. 

 All four gills marsupial. There is hardly any difference in structure 

 between the inner and outer gill. When gravid, the water-tubes 

 (ovisacs) (In nol expand much, and their lumen remains nearly cylin- 

 drical. Placentae also subcylindrical, generally red in color, rather 

 pei sistent, and discharged whole. Glochidia rather small, subovate, 

 without hooks. 



Type: F. trigona (Lea), which (if. Walker, 1910ft, p. 24) should 

 bear the name andata (Barnes). 



Fusconaja undata (Barnes). 



About a half dozen specimens of the form from Lake Erie have been 

 examined, and in July, i<)io, I found a few gravid specimens. Mr. 

 II. h. Wheeler sent two males, and >i\ females (one of the latter 

 gravid) from the Ouachita River, Arkadelphia, Arkansas, collected 

 March 21, [911. 



This form agrees in all essential points with /•'. rubiginosa. The ova, 

 placenta', and sexual glands have the same red color. The soft parts 

 are les> inclined to orange, are paler, and often whitish and cream- 

 colored. Simpson (in Baker, 1898, p. 76) gives a rather meager de- 

 scription. The glochidia are unknown, all specimens found by myself 

 had only eggs. 



The gravid female from Arkadelphia was just beginning to charge 

 the gills. This early date (March 21) should be noted. 



Fusconaja rubiginosa (Lea). 



Numerous specimens, in all conditions, have been examined, all 

 collected in the smaller creeks of the Ohio drainage in western Penn- 

 sylvania. 



This species is typically tachytictic, but the breeding season is 

 rather long, from the middle of May to the beginning of August. 

 In the case of single individuals it is probably much shorter. 



Descriptions of the soft parts have been given by Lea (Obs., X, 

 [863, p. 416) and Simpson (in Baker, [898, p. 78). 



Edges of the mantle drawn together by the gill-diaphragm, thus 

 separating the anal and branchial openings. Anal opening closed 

 above by a very short mantle-connection, thus forming a very large 

 supra-anal; but this mantle-connection is very inconstant and de- 



