EXPLANATION OF PLATE IV. 
1. — Photograph of type specimen ($ ) of Trygon microps. This specimen mea- 
sured 6 ft. 6 in. across the disk. 
2 . — Photograph of female specimen of T. zugei, x 
3- — Photograph of female specimen of Pteroplatea zonura (considerably reduced). 
4- — Photograph of young specimen of Pt. tentaculata , x c. A piece of white 
paper has been placed beneath the left tentacle. 
5- — Photograph of a male specimen of Aetohatis flagellum, x c. 
