54 
HAROLD S1DEBOTHAM. 
DESCRIPTION OF PLATE V, 
Illustrating Mr. Harold SidebothanPs “Note on the Fate of 
the Blastopore in Ran a temporaria.” 
Reference Letters. 
at. Alimentary canal, all. Allantois, bl. Blastopore, ep. Epiblast. m. 
Mesoblast. n. c. Neureuleric canal. not. Notochord, n. y. Neural groove. 
p.a.g. Post- anal gut. pr. Proetodseum. n. c. Neural canal, r. d. Rectal 
diverticulum, sp. c. Spinal cord. x. Yolk. 
Figs. 1 — 5. — Median vertical lougitudinal sections. 
Fig. 1. From an embryo with three mesoblastic somites. The neural 
groove is still open, except at the anterior end ; the blastopore is widely open ; 
and the rectal diverticulum well marked. 
Fig. 2. From an embryo with five mesoblastic somites. 
Fig. 3. From an embryo with six mesoblastic somites. 
Fig. 4. From an embryo with seven mesoblastic somites. 
Fig. 5. F’rom an embryo with eight to nine mesoblastic somites. 
Figs. G and 7. — Transverse sections from an embryo slightly older than 
Fig. 1. 
Fig. 6. Taken along line a — a in Fig. 1. 
F’ig. 7. Taken along line b — b in Fig. 1. 
