VASCULAR SYSTEM OF PHERETIMA 851 
of the blood-system of Pheretima and the course of blood- 
flow about which, even in Lumbriecus, there has been 
a great divergence of opinion amongst the various observers. 
Some of the observations were made in India, but in this 
country, besides having an opportunity of examining the 
two English genera Lumbrieus and Allolobophora, 
IT was able to complete my work on Pheretima, having 
been lucky to obtain specimens of this Oriental form in the 
Lily-house of Kew Gardens. 
The work was carried out in the Department of Comparative 
Anatomy at Oxford. Iam indebted to Professor E. 8. Goodrich 
for his keen interest in my work; he has made valuable 
suggestions, and has also found time to read through and correct 
the manuscript of the paper. 
Although essentially the blood-systems of both Lum- 
bricus and Pheretima can be reduced to a common 
type, there are important differences in the system in the two 
genera, which I have indicated in the text. Pheretima 
resembles Allolobophora rather than Lumbricus go 
far as the blood-system in the general body-region is concerned, 
while the system differs in important respects from that of 
Megascolex. As regards the course of. the blood-flow studied 
by holding the vessels with fine forceps, by cutting the vessels 
and observing the direction of blood-flow, and by a study of 
the valves, I am led to confirm the observations and con- 
clusions of Johnstone (10 and 11) and to reject part of Bourne’s 
theory of the course of the circulation (1). 
The typical arrangement of the blood-system in P here- 
tima is found behind the fourteenth segment, being meta- 
merically repeated behind that segment. In the first fourteen 
segments, on the other hand, this typical arrangement is con- 
siderably modified, this modification, together with that shown 
inthe digestive, reproductive, and nervous systems, being spoken 
of as cephalization. It will be convenient, therefore, to 
describe, as Harrington (8) does in the case of Lumbricus, 
first, the typical arrangement as it occurs in the region of the 
body of the worm behind the fourteenth segment, and then the 
