ORTMANN: FAMILIES AND GENERA OF NAJADES. 363 
Fic. 3. Unio pictorum (Linneus). Male—Moschinska River, Prov. Posen, 
Germany, W. Israél don.—Carn. Mus., No. 61, 4,938. Horizontal cross section 
through left inner (7) and outer (0) gill, showing gill structure of the male. 
Fic. 4. Unio pictorum (Linneus). Sterile female——Lake Storkow, Prov. 
Brandenburg, Germany, W. Israél don.—Carn. Mus., No. 61, 4,939. Horizontal 
cross section through left inner (7) and outer (0) gill, showing marsupial structure 
in outer gill only. 
Fic. 5. Unio crassus consentaneus (Rossmessler). Sterile female.—Danube 
River, Buda-Pest, Hungary, W. Israél don.—Carn. Mus., No. 61, 4,996. Hori- 
zontal cross section through left inner (7) and outer (0) gill, showing marsupial 
structure in the outer gill only. (This section is more toward the base of the gills 
than in Fig. 4.) 
Fic. 6. Arcidens 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. 
Fic. 7. Anodonta cygnea (Linnzus). Sterile female-—Obra South Canal, 
Sepno, Prov. Posen, Germany, W. Israél don——Carn. Mus., No. 51, 4,956. Hori- 
zontal cross section through Jeft inner (7) and outer (0) gill, showing marsupial 
structure of the sterile female in the outer gill. 
Fic. 8. Anodonta cygnea (Linneus). Gravid female-—Mogelnitza River, Prov. 
Posen, Germany, W. Israél 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. 
Fic. 9. Anodonia complanata Rossmessler. Gravid female.—Woernitz River, 
Dinkelsbuehl, Bavaria, Germany, W. Israél don.—Carn. Mus., No. 61, 4,958. 
Horizontal cross section through left inner (7) and outer (0) 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. 
Fic. 10. Obliquaria 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. 
Fic. 11. Dyromus 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 
placente and the glochidia. 
EXPLANATION OF PLATE XIX. 
Glochidia of Najades. 
Photographed with Bausch & Lomb Objective, % inch. 
Fic. 1. Elliptio complanatus (Dillwyn).—Meniolagomeka Creek, Smith Gap, 
Monroe Co., Pa., coll. June 14, t910.—Carn. Mus., No. 61, 4,631. 
Fic. 2. Anodonta cygnea (Linneus).—Moschinska River, Prov. Posen, Ger- 
many, W. Israél don.—Carn. Mus., No. 61, 4,954. 
