74 OTTO F. KAMPMEIER 
V.JUS.€xT. dex. 
Fig. 10 (A) Photomicrograph of a transverse section through the right 
ventral cephalic region of a 6-mm. embryo of Bufo vulgaris (IX. E. C., series B 53, 
slide 1, section 90). X 690. (B) Section through the left ventral cephalic 
region of a 7-mm. embryo (series B 52, slide 1, section 84). XX 690. v. jug. ext. 
dex. and sin., vena jugularis externa dextra and sinistra; lym., anlagen of the 
primary maxillary sinus. 
