Fic. 1. Cephalic veins of a late embryo of Tropidonotus natrix, head 7.5 
mm. long. X 24. After Grosser and Brezina, gs. 
g. Ss. p., ganglion spheno-palatinum; s. o., sinus orbitalis; s. V., “ secundare 
Verbindung” (see text); v. ¢. a., vena cerebralis anterior; v. c. m., vena cere- 
bralis media; v. c. m. s., vena cerebralis media secunda; v. 1. c., vena longi- 
tudinalis cerebri; v. c. p., vena cerebralis posterior; v. j. i., vena jugularis 
interna; v. m., vena mandibularis; v. ma., vena maxillaris; V. 2-3, ganglion of 
second and third branches of trigeminus; VJ, 1X, X, cranial nerves. 
