192 W. F. E. WELDON. 



EXPLANATION OF PLATES XVIII & XIX, 



Illustrating Mr. W. F. R. Weldon's Paper "Oq the Supra- 

 renal Bodies of Vertebrata." 



Complete List of Reference Letters. 



Al. Alimentary canal. Ao. Aorta. Bv. Blood-vessel, gl. Glomerulus. 

 g. ep. Glomerulus epithelium, pe.ep. Peritoneal epithelium. Mes. Mesentery. 

 V. c. Vena cava. s. t. Segmental tubule. *. sir. Testicular tubule, s. r. 0. 

 Suprarenal blastema. W. r. Wolffian ridge. 



The figures were in all cases drawn by the aid of a Zeiss's camera lucida. 



Fig. 1. — Transverse section through a glomerulus of an embryo of Lacerta 

 muralis with twenty-one protovertebrse. 



Fig. 2. — Similar section through an embryo with twenty-three protover- 

 tebrse. 



Fig. 3. — Similar section through an embryo 8 mm. long. 



Fig. 4. — Similar section from an embryo 10 mm. long. 



Fig. 5. — Similar section from an embryo of 11 mm. 



Fig. 6. — Similar section from an embryo of 13 mm. 



Fig. 7. — Similar section from an embryo of 18 mm. 



Fig. 8. — Transforming blastema of teleostean kidney, copied from Emery. 



Figs. 9 and 10. — Two consecutive sections through an embryo of Pris- 

 tiurus melanostomus of 8 mm. 



Figs. 11 — 13. — Consecutive sections from an embryo of Pristiurus of 8J mm. 



Figs. 14 and 15. — From an embryo of Pristiurus of 10 mm. 



Fig. 16. — From an embryo of Pristiurus slightly older than that figured in 

 figs. 14 and 15. 



Fig. 17. — From a five-day chick. 



Fig. 18. — From a seven-day chick. 



Fig. 19. — From a nine-day chick. 



