eire.or.si. 
mox.prim. 
cire.or.si. 
méx.prim. 
V.jug.exf. 
Sin. 
Fig. 1 Transverse section of a 13-mm. embryo of Bufo vulgaris at the level 
of the mouth. X 50. circor. si. max. prim., circumoral division of the primary 
maxillary sinus; cav. or., cavum oris; lab. or., labial structures of the larval suck- 
ing mouth. 
Fig. 2 Same, at the level of the eyes. X 50. mand. si. max. prim., mandi- 
bular division of sinus lymphaticus maxillaris primigenius; v. jug. ext. dex. and 
sin., vena jugularis externa dextra and sinistra; a. car. ext. dex. et sin., arteria 
carotis externa dextra and sinistra; cav. or., cavum oris. 
63 
THE AMERICAN JOURNAL OF ANATOMY, VOL. 30, NO. 1 
