PLATE 5e. 



HEART. 



Fig. 1. HEPTR.\NCHiAa PERLO. M. C. Z. 945 (Page 21). Fig. 2. Scaph.^norhynchus owstoni. 

 M. C. Z. 1048 (Page 28). Fig. 3. Orbctolobds j.\ponicu.s. M. C. Z. 1038 (Page 50). Fig. 4. 

 Cephai-o.scyllidm nMBRATiLE. M. C. Z. 1044 (Page 80). Fig. 5. Lsoru.s pdnctatd.s. M. C. Z. 

 1249 (Page 36). Fig. 6. Prwtiophorus japonicu.s. M. C. Z. 1045 (Page 246). Fig. 7. Rhinoba- 

 Tus PERCELLEN.S. M. C. Z. 430 (Page 278). Fig. 8. Di.scobatos sine.nsis. M. C. Z. 1120 (Page 

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

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



Rather generally the number of rows of valves in the conus of the Antacea decrea.ses with advance in 

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

 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 67, fig. 1-6. 



