270 ~=69©George 8. Huntington and Charles F. W. MeClure. 
1. Gradual reduction of the multiple early veno-lymphatico- 
venous connections, but retention, in some cases, of the primary 
precardinal connections of tributaries 1, 2, and 3. 
2. The gradual establishment of two definite points of com- 
munication between the promontory and the dorsal (Tap C) 
and ventral (Tap B) veno-lymphatic plexuses, respectively, which 
are usually the last to be retained during the separation process and 
which correspond, approximately, in their position to the points 
where the jugular lymph sae taps the venous system in the adult. 
3. Clear differentiation of the veno-lymphatic plexus into 
three primary divisions and the beginning of a fusion between the 
two divisions of the ventral plexus. 
4. Complete separation of the dorsal and ventral veno-lym- 
phatic plexuses by a clear interval which serves for the transit of 
the thyro-cervical artery. 
5. Separation of the dorsal plexus from the anterior end of the 
anlage common to the primitive ulnar vein and primitive ulnar 
veno-lymphatie. 
6. Separation from this common anlage of a small parallel 
channel which forms the primitive ulnar veno-lymphatic. This 
veno-lymphatic joins the dorsal plexus and remains connected with 
the caudal end of the same after the primitive ulnar vein has been 
replaced in the drainage of the anterior limb by the definite sub- 
clavian vein. 
7. The presence of a number of detached veno-lymphatics 
which subsequently fuse with one another and with the three 
primary divisions of the plexus in establishing the single veno- 
lymphatic sac of later*stages. 
8. The definite establishment of theanlage of the cephalic vein. 
TWO EMBRYOS ILLUSTRATING THE LATERAL DISPLACEMENT 
OF CERTAIN VENO-LYMPHATICS WHICH ARE SECONDARILY 
SEPARATED BY FENESTRATION FROM THE CAUDAL DIVISION 
OF THE VENTRAL VENO-LYMPHATIC PLEXUS, 
Series 112, 10" Embryo 
Series 118, 10™™ Embryo 
As the result of an excessive retiform development in the caudal 
division of the ventral veno-lymphatic plexus it frequently, 
