OF ARTS AND SCIENCES. 127 



Fig. 11. The tail lias now the shape of that of the adult; the merest trace of 

 the embryonic caudal remains. 

 „ 12. Fig. 11 somewhat magnified, to show the cartilages supporting the 

 permanent and tlie accessory fin-rays of the tail, as well as the 

 urostyle with last ossified vetebra. 



The young Flounder of Fig. 1 measured 6"""- in length ; that of Fig. 12 meas- 

 ured 18""™-; the whole change of the tail, from the straight notochord of 

 Fig. 1 to the rounded tail of Fig. 12, took place in about three weeks, judging 

 from the specimens fished up. 



PLATE II. 



Tails of Embryos of Young Fishes. 



Figs. 1-4. Atherina, respectively 5"^-, Q™™-, 10"""-, ll"""- long. 

 Fig. 5. Batrachus. O""™- long. 



„ G. Lumpus. 4™"'- long 



„ 7. Ctenolabrus. 6™"- long. 



„ 8. Poronotus. 7™™- long. 



„ 9. Young Lophius with straight notochord. About S™™- long. 



„ 10. Heterocercal tail of young Lophius. 20™- long. 



„ 11. Flesiiy pectoral of same, seen from the side. 



„ 12. Same seen from above. 

 Figs. 13, 14. Gasterosteus. 



„ 16,17,18. Phycis. Fig. 16/ 3""»-, 8"""-, IS""-. 

 Fig. 19. Cod. 20™"- long. 



„ 20 and Fig. 18. Magnified. (Phycis.) 



