382 ALFRED GIBBS BOURNE. 
opening into the hearts of this segment. Their connection, and that of the 
hearts, with the dorsal vessel is also shown. 
Fic. 34.—M. grandis. Diagram of the arrangement of the blood-vessels 
on one side of a segment. The ventro-tegumentary vessel and the branch of 
the subneural are seen playing opposite roles. The dorso-tegumentary is seen 
to join the branch of the subneural at z. The meaning of the various arrows 
is explained in the text, p. 335. 
Fic. 35.—M. sapphirinaoides. Small arteries and veins in the body- 
wall seen in a longitudinal section. Sept. Septa. Zp. Epidermis. Cm. 
Circular muscular layer. 7. m. and /. m*. Inner and outer longitudinal 
muscular layers. 
Fic. 36.—M. sapphirinaoides. Portion of the epidermis from the 
same section as in the preceding figure. The actual “ capillaries” are seen. 
Fic. 37.—M. grandis. Blood-vessels on a portion of the nephridium. 
Fic. 38.—M. grandis. Diagram of the arrangement of the blood-vessels 
in the intestinal wall. Letters as before. The arrows show the direction 
of the blood-flow. 
Fie. 39.—M. grandis. Portion of the dorsal vessel cut open in the 
dorsal median line to show the apertures of the dorso-tegumentary and dorso- 
intestinal vessels. «. Valve preventing backward flow in the dorsal vessel. 
y. Valve at the mouth of the dorso-intestinal vessel preventing outward 
flow. 
Fie. 40.—M. grandis. View of the hinder surface of septum 7/8. 
The relative positions at which the cesophagus, Oe., the dorsal vessel, D. Y. 
the ventral vessel, V. V., the latero-longitudinal vessels, Z. Z., and the nerve 
cord, z., pass through the septum are shown. The spermatheca, Sp., and its 
duct are shown. The spermathecal duct penetrates the septum at 2. and 
runs in the thickness of the septum, as shown by the dotted lines, to the 
copulatory pouch, which is embedded in the thickness of the body-wall. 
The sete are inserted, although, of course, they really lie further forward. 
Fic. 41.—M. grandis.—Diagram of a section across the body in Segment 
vit to show the ‘ mesenteries” marked by thick black lines (each really 
double) which join the longitudinally running vessels to the intestinal and 
body-walls. Letters as before. 
PLATE 27. 
Moniligaster grandis. 
Fie. 42.—Plan of an entire nephridium of the left-hand series, drawn as 
though the worm were opened along the dorsal median line and flattened 
out. V. V. Position of the ventral median line, i.s., ¢.s.; 0.8.,0.s Inner 
