PLATE 1 
EXPLANATION OF FIGURE 
28 Reconstruction of the larger haemal and lymphatic vessels in the head 
and anterior trunk region of a 7.5-mm. embryo of Bufo lentiginosus (K. E. C., 
series B31), dorsal view. X 50. 
Structures not colored: lymphatics, anterior end of spinal cord and brain, 
olfactory, optic, and auditory vesicles, and pronephros and its duct; the latter 
structures omitted on the right side. 
Lymphaties: si. circ. or., cireumoral division of the sinus maxillaris primi- 
genius; st. mand., mandibular division; sz. temp., temporal division; sz. pericard., 
pericardial division; lym. jug., lymphatica jugularis; cor. lym. ant. dex. and sin., 
cor lymphaticum anterius dextrum and sinistrum; lym. lat., lymphatica lateralis. 
Veins (blue): A portion of the sinus venosus is shown ventral to the myelen- 
cephalon joined by the hepatic sinusoids, the external jugular veins and cuvierian 
ducts. The external jugular accompanies the pericardial lymphatic and anteri- 
orly receives two branches, a medial (hidden by the mesencephalon), probably 
the anlage of the vena lingualis, and a lateral, lying closely against the inner side 
of the principal and cireumoral divisions of the primary maxillary sinus and repre- 
senting the future vena mandibularis and branches. In the region of the prone- 
phriec sinusoids (a large section omitted on the right side) the cuvierian duct is 
joined by the precardinal or internal jugular, which passes laterally around the 
auditory vesicle and possesses three large tributaries, the vena orbitonasalis, 
the vena ophthalmica, and a large intracranial vein. The lateral and medial 
(subeardinal) divisions of the posteardinal, situated along the pronephric duct, 
and anteriorly, near the pronephric sinus, receive the anterior vertebral vein 
into which the anterior lymph heart opens. 
Arteries (red): The heart, external carotids and ventral roots of the aortic 
arches are not shown in the drawing. The radices aortae are broadly divergent 
in the region of the auditory vesicles, where they connect with the dorsal roots of 
the aortic arches which, as they curve ventrad, lie closely against the inner side 
of the temporal lymphatics. Anteriorly the radices aortae are continued forward 
as the internal carotids which give off in the order named the following impor- - 
tant branches: arteria palatina, a. ophthalmica, and a. carotis cerebralis. The 
pronephric glomeruli branch from the radices aortae immediately anterior to their 
convergence and fusion to form one trunk (ventral to the spinal cord). 
114 
