STUDIES ON THE TURBELLARIA. 437 
the dorsal (posterior) ganglia of the brain by a transverse 
anastomosis going off from the outer angle, so that it has a 
double origin. Neighbouring longitudinal nerves are con- 
nected together by anastomoses between their branches, the 
arrangement of which is subject to variation in different 
individuals. 
On the whole there is a very close correspondence between 
the nervous system of Heterocherus and that of allied 
forms. Owing to the absence of a frontal organ it is not 
possible to distinguish the “anterior and posterior com- 
missures”’ described by vy. Graff, and there is thus an appear- 
ance of greater simplicity in the brain. All the nerve cords, 
except the lateral and those giving rise to the frontal plexus, 
arise from the dorsal part of the brain, and this appears also 
to be a distinguishing feature. 
The two little masses of pigment which represent eyes in 
the Accela, instead of being situated in the epidermis as they 
are stated to be in other members of the group, are embedded 
in the substance of the brain. In this point Heterocherus 
resembles C. schultzii (Delage, 5, p. 131). 
Reproductive Apparatus.—The male reproductive 
apparatus of Heterocherus does not differ in any essential 
respects from that of allied forms. The testes (fig. 2, ¢.) are 
composed of numerous minute lobes, which extend through- 
out the greater part of the length of the body towards its 
dorsal aspect. The two vasa deferentia have no definite 
walls, but are merely of the nature of channels in the paren- 
chyma, which run backwards some little distance from the 
lateral margins, increasing in width as they receive additional 
accessions of spermatozoa from the testicular lobes. At its 
posterior end each vas deferens expands into a wide vesicula 
seminalis (v.), and these bend inwards to meet in a median 
resarvoir at the base of the penis. Into this open the ducts 
of numerous unicellular glands, the secretion of which con- 
sists of, or contains, minute rounded granules. ‘These glands 
appear to correspond to the prostate- or granule-glands of 
other Turbellarians. From the median reservoir a very short 
