318 THE AMERICAN NATURALIST. [VoL. XXXVI. 
In somite X a pair of /ateral vessels come from the dorsal 
vessel and run forward on either side of the cesophagus to the 
pharynx, giving branches to the cesophagus and body wall. 
An anastomosing vessel arises from the lateral near its origin 
in somite X and passes backward to join the large parietal in 
somite XII. From this anastomosis, branches supply the 
seminal vesicles, which are also supplied from the ventral ves- 
sel. Connecting vessels between the laterals and subneurals 
occur in several somites. | 
The only points with regard to the course of the blood flow 
upon which authors agree are that the blood flows forward in 
the dorsal vessel to the hearts, downward in the hearts, and 
backward in the ventral vessel. With regard to the further 
course of the blood Perrier came to the following conclusions. 
(as reported by Bourne and Harrington): the blood flows into 
the dorsal vessel from the parietals and from it through the 
dorso-intestinals ; the ventro-intestinals carry blood from the 
intestine to the ventral vessel; from the ventral it is given to 
the body wall and nephridia and is gathered up from these by 
branches from the lateral neurals and parietals ; the flow in the 
laterals is forward. : 
Bourne (91) studied the blood flow in Megascolex principally 
by holding the vessels with forceps and by cutting them to see 
from which cut end the blood flowed. His conclusions are 
nearly opposite to those of Perrier, namely, that the dorso- 
intestinals empty into the dorsal and the parietals carry blood 
away from it; the ventral gives blood to the intestine through 
the ventro-intestinals; it also gives blood to the body wall and 
nephridia, from which it is carried to the intestine (in Megas- 
colex) by the intestino-tegumentaries. The lateral vessels 
carry blood backward. ——— | : 
Benham (91), working on Lumbricus, agrees with Perrier in 
regard to the blood flow in all vessels. 
Harrington (99) has given a full account of the anatomy of 
the vascular system, with elaborate figures. His descriptions 
and figures, however, do not always agree, e.g., the common 
vessel branching into ventro-tegumentary and ventro-intestinal 
described on page 142 is not shown ín the figures. Harrington 
