PLATE 53. 



Pelvis of PLATOSOMIA. 



Upper and lower surface. 



Fig. 1. Uraptera agassizii. M. C. Z. 549 (Page 367). 



Fig. 2. Narcacion californictjs. M. C. Z. 43 (Page 311). 



Fig. 3. Urobatissloani. M. C. Z. 35 (Page 402). 



Fig. 4. Taeniura lymma. M. C. Z. 23 (Page 399). 



Fig. 5. Dasybatus MARiNus. M. C. Z. 641 (Page 382). 



Fig. 6. Pteroplatea ALTAVELA. M. C. Z. 386 (Page 415). 



The pelvis of the Raiidae, fig. 1, with the lateral prepclvic processes, recalls that of Cyclobatis, 

 a fossil genus. The pelvis of Narcacion, fig. 2, is raioid, but is more arched backward in the middle. 

 Figures 3-6 represent the Dasybatidae, hi which family the organ is more like that of the Antacea, which 

 have neither lateral nor median processes in front of the pelvis. 



