THE DEVELOPMENT OF SVMBIL\NCHUS .ArAHMORATUS. 41 
intestinal veiiD the front end of which is the original vitelline 
vein. Even when the yolk has quite disappeared this large 
subintestinal vein, can be traced right up to the liver. The 
Text-fig. 4 — continued. 
m. 
Sagittal sections through brain of Symbranchus. A. Stage 22. B. 
Stage 24, c. Stage 26. d. Stage 28. e. Stage 30. f. Stage 
34. c. Cerebellum, c. a. Commissura anterior, c. c. Cerebellar 
commissure, ci. Optic chiasma. c. p. Commissura posterior. 
c.pZ. Choroid plexus, e. Epiphysis, /i. Hypophysis, /o c. Habe- 
nular commissure, i. Infundibulum. 1. t. Lamina terminalis. 
m. Mesencephalon, m. o. Medulla oblongata, o. 1. Olfactory 
lobes, o. r. Optic recess, p. Prosencephalon, p, o. c. Post-optic 
commissure, p. r. Hhombo-mesencephalic fissure, p. v. Pi imitive 
brain fold. r. Rhombencephalon, t. Telencephalon, tr. Torus 
transversus. v. c. Yalvula cerebelli. v. t. Yelum transversum, 
II. Optic nerve. 
subintestinal vein is thus seen to pass directly into the hepatic 
vein of the adult, and its junction with the kidney vessels pos- 
teriorly recalls the posterior vena cava in Polypterus. (6). 
