417). 



PLATE 31. 

 POTAMOTRYGONIDAE. 



Fig. 1-2. POTAMOTRYGON CIRCDL-\RIS (P:lge 419). Fig. 3-4. POT.VMOTRYGON L.\TICEPS (Page 



). 



1. Dorsal view. Disk 1.5i inches long. M. C. Z. 291. 



2. Mouth and nostrils. 



3. Dorsal view. Disk 10 inches long. iM, C. Z. iiO'j.'oOr^ 



4. Mouth and nostrils. 



