Marshall and Severin—Anatomy of Ranantra fnsca. 497 
The thoracic ganglion cleared and mounted whole or sectioned 
horizontally shows that it is composed of three fused ganglia. 
(PL XXXV, Fig. 14.) The first and second of these are similar 
in shape, showing quite an anterior-posterior compression and 
differing but little in size, the: anterior slightly the smaller. Each 
give® off three rather large nerves from either size, the first re¬ 
ceiving the two long nerve® from the infra-oesophageal ganglion, 
and the third giving off the two main trunks from its posterior 
end. The last (third) part of the ganglion is elongated along 
its longitudinal axis. The two large nerves coming from it do not 
arise from a single root as shown, (PI. XXXV, Fig. 14) but 
each has as its origin several small roots, most of which arise 
from the posterior margin of the ganglion, but at least one fur¬ 
ther forward than these, and on the side. The position of the 
ganglion cells is shown in the cut- 
in connection with the nervous system, we would mention the 
sense-organs in the antenna. (PI. XXXV, Fig. 15.) In endeav¬ 
oring to make a section of the head, the tip of one of the antennae, 
which had been cut partially open, was noticed on the slide. 
Along one edge there was. a row of setae closed at their tip, but 
eachresting on a little papilla slightly raisedfrom the surface. At 
the base of each seta was a sac hanging free within the antenna. 
These sacs each received at its base a, fine nerve which came from 
a ganglion in the base of the terminal joint of the antenna. 
Within each sac was a structure having the appearance of a small 
ganglion. At the base were a number of nuclei, the rest of the 
sac being filled with fibrillar substance from which fibrils en¬ 
tered the base of the seta. (PI. XXXV, Fig. 16.) 
Reproductive organs; male .—The two testes are found prin¬ 
cipally wfithin the second abdominal segment but generally ex¬ 
tend a short • distance forward into the preceding one. (PI. 
XXXV, Fig, 17.) From a dorsal view each testis appears as an 
elongated body pointed at both ends, the posterior blunter than 
the anterior, with a vas deferens arising from the posterior end of 
each. A closer examination shows at once that the dorsal view 
doe® not, as a rule, reveal the true shape, because, in most speci¬ 
mens examined, one part of the testis is concealed. When all the 
parts are seen (PL XXXVI, Fig. 18),the general shape does not 
become changed but we find that about two-thirds the distance 
from the anterior end there is a large projection from the wall 
of the testis, and that it is here the vas deferens has it® origin. 
32 
