238 George 8S. Huntington and Charles F. W. McClure. 
Series 109, 6.2" Embryo 
Reconstruction of right side, 
Lateral aspect, fig. 29 and 
Medial aspect, fig. 30 
The reconstruction of the right side of this embryo corresponds 
in general with that of the left. The veno-lymphatic development 
and the incident plexiform formation in the area of tributary 4 
shows, however, a greater degree of development. 
The first three dorsal tributaries of the precardinal (1, 2 and 3, 
figs. 29 and 30) are dilated and funnel-shaped, the second and 
third having fused at their bases. This funnel-shaped form pre- 
cedes their separation into veno-lymphatic and dorsal somatic 
components, the former of which will constitute the anlages of the 
cephalic division of the ventral veno-lymphatic plexus. As on the 
left side of this embryo (fig. 27), dorsal tributary 4 (4 in figs. 
29 and 30), has obtained a promontorial connection through the 
formation of a secondary channel (para-precardinal channel), 
separated from the precardinal vein by the elongated fenestra Y 
(fig. 30). In addition, a second fenestra (fig. 30, Z) has developed 
at the promontorial end of the para-precardinal channel, so 
that the latter is now composed in this region of two parallel 
vessels opening separately into the promontory. The plexus at 
this stage presents the condition of tributary 4 just prior to 
its separation into definite veno-lymphatic and dorsal somatic 
components, the former associated with the para-precardinal 
channel to form with it the caudal division of the ventral veno- 
lymphatic plexus. 
The dorsal veno-lymphatie plexus, as on the left side of this 
embryo, is an extensive plexiform sac occupying the dorso-lateral 
aspect of the promontory (figs. 29 and 30). The sac projects for- 
ward over the precardinal vein and is separated from the promon- 
tory by a row of six fenestrae between which it communicates at 
seven points with the main venous system. The anlage common to 
the primitive ulnar vein and primitive ulnar veno-lymphatic has 
