PLATE 66. 



HEART. 



Fig. 1. Heptranchias PERLO. M. C. Z. 945 (Page 21). Fig. 2. Scaphanorhynchus owstoni. 

 M. C. Z. 1048 (Page 28). Fig. 3. Orectolobus japonicus. M. C. Z. 1038 (Page 50). Fig. 4. 

 Cephaloscyllium umbratile. M. C. Z. 1044 (Page 80). Fig. 5. Isurus punctatus. M. C. Z. 

 1249 (Page 36). Fig. 6. Pristiophorus japonicus. M. C. Z. 1045 (Page 246). Fig. 7. Rhinoba- 

 Tus PERCELLENS. M. C. Z. 430 (Page 278). Fig. 8. Discobatus sinensis. M. C. Z. 1120 (Page 

 289). Fig. 9. Narcacion marmoratus. M. C. Z. 42 (Page 305). Fig. 10. Narke japonica. 

 M. C. Z. 1114 (Page 314). 



Rather generally the number of rows of valves in the conns of the Antacea decreases with advance in 

 rank, with increase in specialization. For proof of this compare Heptranchias, fig. 1 , Scaphanorhynchus, 

 fig. 2, Isurus, fig. 5, and Pristiophorus, fig. 6, with Orectolobus, fig. 3, and Cephaloscyllium, fig. 4. In the 

 Platosomia the rule does not hold so well, as is shown by comparing Rhinobatus, fig. 7, of this Plate with 

 greatly specialized types, Plate 57, fig. 1-6. 



