666 MEMOIRS OF THE CARNEGIE MUSEUM. 



EXPLANATION OF PLATE XLVI. 



Gills of Diplqdon paulista (Von Ihering), Diplodon piceus (Lea), Diplodon 



HiLD^ Ortmann, Diplodon burroughianus (Lea), Diplodon mogymirim 



Ortmann, Diplodon berths Ortmann, and Diplodon enno Ortmann. 



All figures represent left gills magnified to twice natural size, the inner gill to the left, 



the outer gill to the right. 



Fig. 1. Diplodon paulista (Von Ihering), from Rio Tiete, Mogy das Cruzes, Sao 

 Paulo, Brazil. Carn. Mus. Cat. No. 6L9294. Gills of female (No. 4). 



Fig. 2. Diplodon piceus (Lea), from Rio Uruguay, Uruguayana, Rio Grande do 

 Sul, Brazil. Carn. Mus. Cat. No. 6L5S62. Gills of female (No. 7). 



Fig. 3. Diplodon hild(p Ortmann, from Rio Jacuhy, Cachoeira, Rio Grande do 

 Sul, Brazil. Carn. Mus. Cat. No. 6L5864. Gills of female (No. 15) (Shell of this 

 specimen figured on Plate XXXVII, fig. 2). 



Fig. 4. Diplodon burroughiamis (Lea), from pond along Rio Negro, Santa Isabel, 

 Uruguay. Carn. Mus. Cat. No. 61.5859. Gills of female (No. x). 



Fig. 5. Diplodon mogymirim Ortmann, from creek (tributary to Rio Mogy Guassu) 

 Mogy Mirim, Sao Paulo, Brazil. Carn. Mus. Cat. No. 61.9260. 



Fig. 5a. Gills of male (No. 28). 



Fig. 5b. Gills of young female (No. 18). 



Fig. 5c. Gills of adult female (No. 44). 



Fig. 6. Diplodon bertJue Ortmann, from Rio Jacuhy, Cachoeira, Rio Grande do 

 Sul, Brazil. Carn. Mus. Cat. No. 61.5865. Gills of female (No. 21). 



Fig. 7. Diplodon enno Ortmann, from Rio Grande (Sao Francisco drainage), 

 Boqueirao, Bahia, Brazil. Carn. Mus. Cat. No. 61.9264. 



Fig. 7a. Gills of young female (No. 7). 



Fig. 7b. Gills of nearly adult female (No. 2) (Shell of this specimen figured on 



Plate XXXVIII, fig. 8). 



