of the Fishery Board for Scotland. 



283 



Plate XIV. 



Fig. 8. Transverse section of an embryo 7 days 6| hours old in region of hind- 

 brain, x 250. 



Fig. 9. Transverse section of an embryo 7 days 194 hours old in the same region 



as the preceding, x 250. 

 Fig. 10. Longitudinal vertical section (nearly median, but slightly oblique) of an 



embryo 8 days 6| hours old in region of mid- and hind-brain, x 250. 

 Fig. 11. Longitudinal vertical section (oblique) of an embryo 8 days 19| hours old 



in region of mid- brain, x 250. 

 Fig. 12. Longitudinal vertical section (median) of an embryo 10 days 7| hours old 



through the heart, x 250. 

 Fig. 13. Longitudinal vertical section (nearly median) of an embryo 10 days 19^ 



hours old in region of hind-brain, x 250. 



Plate XV. 



Fig. 14. Longitudinal vertical section (nearly median) of an embryo 14 days 20J 



hours old through mesenteron and liver, x 200. 

 Fig. 15. Transverse section (combined from two sections) of an embryo 13 days 



7\ hours at the point where the ductus choledochus opens into 



gut, x 200. 



Fig. 16. Transverse section of an embryo 7 days 16J hours showing a dorsal diver- 

 ticulum of the gut, x 250. 



Fig. 17. Transverse section of an embryo 8 days 19^ hours old showing a similar 

 diverticulum, x 250. 



Fig. 18. Transverse section (sagittal) of an embryo 7 days 19^ hours old in the 



region of pronephros, x 250. 

 Fig. 19. Transverse section of an embryo of the same age as the preceding in the 



region pronephros, x 350. 

 Fig. 20. Transverse section of the same embryo as Fig. 19, but three sections more 



anteriorly, x 350. 



Fig. 21. Transverse section of an embryo 8 days 16^ hours old through anterior 

 end of segmental duct, x 250. 



Plate XVI. 



Fig. 22. Transverse section of an embryo 13 days 20| hours old in the region of the 

 pectoral fin, x 200. 



Fig. 23. Transverse section of the same embryo as the preceding, but more 

 posterior, x 200. 



Fig. 24. Longitudinal vertical section (slightly oblique and combined from two 

 sections) of an embryo 19 days — 2 days hatched — through the gut and 

 renal organ, x 80. 



Fig. 25. Longitudinal vertical section of an embryo 22 days — 5 days hatched — 



through the same region as the preceding, x 80. 

 Fig. 26. Longitudinal vertical oblique section of an embryo 13 days 20^ hours old, 



showing the passage from the urinary vesicle to the rectum, x 250. 

 Fig. 27. Transverse section of an embryo 22 days — 5 days hatched — through the 



pronephros and glomerulus, x 200. 

 Fig. 28. Transverse section of an embryo 26 days — 9 days hatched — through the 



same region as the preceding, x 200. 



