MONILIGASTER GRANDIS, A. G. B. 327 
but these are connected one with the other across the middle 
line, and a short median vessel puts them in connection with 
the dorsal vessel, while into the necks open the two main 
trunks of the latero-longitudinal subneural system (fig. 33). 
At the lower (or distal) extremity each heart opens into a 
bulb, between which and the heart proper is a sphincter 
muscle. This bulb opens directly into the ventral vessel in 
the case of the three anterior pairs of hearts, but with the 
intervention of a short neck in the case of the most posterior 
pair of hearts (fig. 33). 
Capillary Networks.—These may be spoken of as peri- 
pheral networks and intestinal networks. 
Peripheral Networks.—Under this term I include not 
only the capillary networks of the body-wall and septa, but 
those of the nephridia, generative organs, walls of the large 
blood-vessels (dorsal vessel and hearts), and, indeed, those of 
all the viscera with the exception of the intestinal walls; the 
capillaries of these latter are really central as compared with 
the others, but are conveniently termed intestinal networks. 
The peripheral networks are extremely well developed 
throughout, the capillaries being always perfectly clear and 
distinct. The smallest capillaries measure not more than —,. 
of an inch in diameter. There is no trace of any lacunar 
structure. 
There is a sort of fascination in following out these exquisite 
networks, and I have spent much time in so doing, but it 
would serve no purpose to describe them in detail. I merely 
mention this to emphasise the fact that figs. 35—37 are no 
imaginary diagrams, but accurate drawings of actual prepara- 
tions. Perhaps the most striking feature of these networks is 
the strict parallelism which obtains throughout between 
“artery ’’ and “vein.” They are not, indeed, strictly speak- 
ing, networks; each small “ artery ”’ loops round and becomes 
a small “ vein.” 
In dealing with Megascolex ceruleus I had only ascanty 
supply of specimens, and was consequently unable to study 
these capillary networks in such detail, I used the term 
