Ortmann; Families and Genera oi Najades. 363 



Fig. .i. Unio pictorum (Linn;eus). Male Moschinska River, Prov. Posen, 

 Germany. W. Israel don. — Cam. Mus., N >. 61, i.o^s. Horizontal cross section 

 through left inner (*) ami outer (o) gill, showing gill structure of the male. 



Fig. \. r>t!.< pitt<>ru»i (Linnaeus). Sterile female. — Lake Storkow, Prov. 

 Brandenburg, Germany. W. Israel don.— Carn. Mas., No. 6r. 4,939. Horizontal 

 ection through left inner (t) and outer (o) gill, showing marsupial structure 

 in outer gill only. 



Fig. 5. Unio crassus consentaneus (Rossmaessler). Sterile female. — Danube 

 River. Buda-Pest, Hungary. W. Israel don. — Carn. Mus., No. 61, 4,996. Hori- 

 zontal cross section through left inner (i) and outer (o) gill, showing marsupial 

 structure in the outer gill only. (This section is more toward the base of the gills 

 than in Fig. |> 



Fig. 6. . 1 rcidens confragosus (Say). Sterile female. — Bayou Pierre, De Soto 

 Par., La., L. S. Frierson coll. — Carn. Mus., No. 61, 4,701. Horizontal cross section 

 through left outer gill, showing marsupial structure of the sterile female, with 

 indications of the places of the lateral water-tubes. 



Fig. 7. AnoJonta cygnea (Linnaeus). Sterile female. — Obra South Canal, 

 Sepno, Prov. Posen, Germany, W. Israel don. — Carn. Mus., No. 51, 4,956. Hori- 

 zontal cross section through left inner (0 and outer (o) gill, showing marsupial 

 structure of the sterile female in the outer gill. 



FlG. 8. Anodonta cygnea (Linnaeus). Gravid female. — Mogelnitza River, Prov. 

 Posen, Germany, W. Israel don. — Carn. Mus., No. 61, 4,953- Horizontal cross 

 section through left outer gill (marsupium), being partially filled with ova, and 

 showing the beginning of the formation of the lateral water-tubes by folds arising 

 from the septa. 



Fig. 9. A nodonta complanata Rossmaessler. Gravid female. — Woernitz River, 

 Dinkelsbuehl, Bavaria, Germany, W. Israel don. — Carn. Mus., No. 61, 4.958. 

 Horizontal cross section through left inner (i) and outer (o) gill, showing character 

 of the marsupium in the outer gill, charged with glochidia. The lateral water- 

 tubes are somewhat irregular in this specimen, the marsupium being only partly 

 filled. 



Fig. 10. Obliquarla reflexa Rafinesque. Gravid female, partly discharged. — 

 Bayou Pierre, De Soto Par., La., L. S. Frierson coll. Aug. 6, 1910. — Carn. Mus., 

 No. 61, 4.755. Vertical cross section through a discharged ovisac of the right 

 marsupium, showing opening at its distal end. 



Fig. ii. Dromus dromas (Lea) . Gravid female. — Cumberland River, Rowena, 

 Russell Co., Ky., B. Walker don. — Carn. Mus., No. 61, 4,969. Horizontal cross 

 section through marsupial part of left outer gill, showing arrangement of the 

 placentae and the glochidia. 



Explanation of Plate XIX. 

 Glochidia of Najades. 



Photographed with Bausch & Lomb Objective, % inch. 



Fig. i. Elliptio complanatus (Dillwyn). — Meniolagomeka Creek, Smith Gap, 

 Monroe Co., Pa., coll. June 14, 1910. — Carn. Mus., No. 61, 4,"63i. 



Fig. 2. Anodonta cygnea (Linnaeus). — Moschinska River, Prov. Posen 

 many. \V. Israel don. — Carn. Mus., No. 61, 4,954- __ 





