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Annals of the Carnegie Museum. 



tube; the latter forms the ovisac, containing the eggs and embryos, 

 and this ovisac is also closed at the base of the marsupium by a 

 fine membrane. 26 



The eggs and glochidia fill the ovisacs without forming placentae, 

 and the glochidia are discharged through the anal opening in rather 

 irregular masses. Glochidia 27 rather large, triangular, with hooks. 

 They are about as long as high, 0.35 mm. (see Plate XIX, fig. 2). 



Having seen only alcoholic material I refrain from describing the 

 colors of the soft parts. 



Anodonta complanata Rossmaessler. 

 See also Ortmann, 1911c, p. 22. 

 Six specimens from Dinkelsbuehl, Bavaria, and ten specimens from 

 Buda-Pest, Hungary, are at hand, received from W. Israel. Among 

 them are gravid females. 



Fig. 14. Anodonta complanata Rossrruessler. Male, from Wcernitz River, 

 Dinkelsbiihl, Bavaria. (Cam. Mus., No. 61, 4,958-) 



Inner edge of anal opening with very fine papillae. Gills (see Plate 

 XVIII, fig. 9) essentially of the same structure as Anodonta cygnea, 



-' That the lateral water-tubes are actually parts cut off from the original water- 

 tube by folds is conclusively shown by fig. 8, Plate XVIII. This is a slide made 

 from a female, in which the eggs were just beginning to go into the marsupium. 

 Attention should be called to the fact that in this species I never found the lateral 

 water-tubes complete. This may be due to the fact that all my material was col- 

 lected early in the breeding season. Nevertheless, some of the specimens had fully 

 developed glochidia. 



27 The glochidia have been figured by Fleming (1875, pi. 4, fig. 4) and Schierholz 

 (1889, pi. 2, fig. 26), their measurements, 0.35 mm., have been given by Harms 

 (1909, p. 332) and Haas (1910a, p. no). 



