246 George S. Huntington and Charles F. W. McClure. 
lymphatic complex of 4 and of the para-precardinal channel has 
become confluent with the dorsal veno-lymphatic plexus. 
An elongated diverticular process near the promontory (A P, fig. 
33) opens on the left side into the para-precardinal channel. The 
same element is present on the right side (AP, fig. 35) but, in 
this case, does not terminate in the para-precardinal channel, but 
in the dorsal somatic component of precardinal tributary 4 (4S) 
which is still but incompletely differentiated from the para-pre- 
cardinal channel. 
The dorsal somatic component of 4 (4S, fig. 34) is composed 
of two parallel channels, united anteriorly by a short transverse 
branch, which open into the dorso-medial circumference of the 
promontory by a common trunk. The ventral and longer of 
these two channels follows closely the dorso-medial circumference 
of the precardinal vein and terminates cephalad in a blind ex- 
tremity, near which it communicates (figs. 33 and 34, at A) 
with a veno-lymphatic component (4VL) of tributary 4. About 
midway in its course the ventral channel also communicates with 
the precardinal vein (fig. 34, X’), thus retaining its primary con- 
nection with the main vein as in figs. 22, 23 and 24, as does also 
the veno-lymphatic derivative of tributary 4 (fig. 33, X). The 
dorsal smaller subdivision of the somatic element of tributary 4 
terminates cephalad in a blind end. 
The dorsal division of the veno-lymphatic plexus is an extensive 
multi-fenestrated product of the dorso-lateral portion of the prom- 
ontory, the plexiform network extending caudad along the line 
of the future separation of the primitive ulnar from the main 
posteardinal vein. 
The promontory in series 138 (figs. 33 to 36) is a well-defined 
area. The external jugular anlage opens into the promontory 
near the latter’s point of confluence with the duct of Cuvier. 
Series 188, 7" Embryo 
Reconstruction of right side, 
Lateral aspect, fig. 35 and 
Medial aspect, fig. 36 
The right side of the embryo presents the same clear differen- 
tiation into dorso-lateral veno-lymphatiec and dorso-media] 
