STUDIES ON EARTHWORMS. 299 
course of the blood. a. Alimentary canal. J. w. Body wall. ca. Ceelom. 
Com. “Lateral heart.” com. spt. Vessel to body wall from the lateral heart. 
D. Dorsal trunk. 7. w. Wall of the alimentary canal. JZ. Longitudinal lateral 
trunk. JZ. al. Vessel from the alimentary canal to the lateral trunk. L. spd. 
Vessel from septum and body wall to lateral trunk. z.c. Nerve-cord. V. Ven- 
tral trunk. V. spt. Vessels from the ventral trunk to septum and body wall. 
Fic. 20.—A diagrammatic section through the body, to show the arrange- 
ment of the vascular trunks posteriorly to somite x1m. The arrows indicate 
the course of the blood. a/. Alimentary canal. 4. w. Body wall. ca@. Colom. 
D. Dorsal trunk. d. iz¢. Vessel from the dorsal trunk to the wall of intes- 
tine. d. spt. Vessel from septum, &c., to the dorsal trunk. 7... Wall of 
intestine, with network of vessels on it. .c. Nerve-cord. 7. Typhlosolar 
trunk. 7. izé. Vessel from wall of intestine to typhlosolar trunk. ¢y. Typhlo- 
sole. V. Ventral trunk. V. int. Vessel from ventral trunk to enter the 
network on the wall of intestine. V. spt. Vessel from ventral trunk to body 
wall, &c. The vertical vessel from typhlosole to dorsal trunk is not lettered. 
Fic. 21—A complete nephridium. c.v. Blind end of nephridial vesicle. 
ne. f. Nephridial funnel. ze. m. Sphincter muscle of the nephridiopore (ve. o.). 
ne.t. Nephridial tubules, much twisted and forming a rosette-shaped mass. 
ne. v. Nephridial vesicle. 
Fig. 22.—The nephridial funnel and neighbouring portion of a tubule after 
passing through the septum. cz. Long cilia at the internal opening of the 
funnel. ¢.¢. Connective tissue round the lumen (/.) of the tubule. 
Fig. 23.—A more enlarged drawing of the funnel, showing large connective- 
tissue cells. Letters as before. (Drawn by A. G. Bourne.) 
Fie. 24.—Four ciliated columnar cells from the nephridial funnel. ci. Cilia. 
a. Nuclei. 
Fig. 25.—The first nephridium, showing the much elongated region of the 
vesicle between the tubules and the nephridiopore. c.v. Blind end of vesicle 
(ue. v.). ne. t. Bunch of tubules. ze. 0. Nephridiopore. 
Fic. 26.—A nephridium from somite x1, showing the position of the 
nephridiopore (we. 0.) about half way between the tubules (we. ¢.) and the blind 
end (c¢. v.). 
Fic. 27.—Interior of the wall of the cesophagus, showing the ridges and 
papille. 
Fic. 28.—Elongated seta, from the anterior region of the body. 
Fic. 29.—Seta from the ventral series in the posterior region of the body. 
Fic. 30.—Has been erased. 
Fic. 31.—The free end of a loop of a nephridial tubule, viewed as a trans- 
parent object, when mounted in glycerine. c. ¢. The connective tissue surround. 
ing the lumina and binding them together. /. The main lumen with thickish 
walls, and lying parallel to (/') the secondary lumen. 2’. The smaller lumina, 
forming a network round the other lumina, surrounded by connective tissue. 
