—— 459 
The exeretory system is, so far as our knowledge extends, quite peeuliar. It 
more nearly resembles that of the eetoparasitic Trematodes than that of the Rhabdo- 
eoeles — the eontraetil, pulsating terminal sae being absent in the latter group and 
almost universally present in the former. 
In its nervous system Temnocephala exhibits one of the highest types of 
development among Platyhelminthes, with its comparatively large brain, the rich 
development of nerves running forwards, the three pairs of posterior trunks, and the 
highly developed subeutaneous nerve-plexus. But in these respects it does not stand 
quite alone. In Zrzstomuwm molae as deseribed by Lang') all these features recur, 
and, but for the less development of the anterior nerves and certain differences in 
the relations of the subeutaneous nerve-plexus (which in Zrzstomum is apparently 
equally eontributed to by all three pairs of trunks), there is a very close correspon- 
dence between the two. T'hough a subeutaneous nerve-plexus is present in Zrrcladidae 
and Polyecladidae, nothing of the kind has been noticed in the Ahabdocoela, and there 
would appear never to be more than one pair of nerve-trunks running backwards 
from the ganglion in that group. The eyes of ZTemnocephala can be exactly matched 
among the Ahabdocoela, and on the other hand, are, in all essential respects, similar 
to those of Zrzstomum. 
In its reproductive apparatus Zermnocephala appears to me to find closer alliances 
among the Rhabdocoeles than among the ectoparasitic Trrematodes: and of the former 
group various Vortieidae as deseribed by v. Graff and others approach very near to 
it in the general arrangement of the parts, as well as in the special character of 
the eirrus. A bursa eopulatrix is absent in Termnocephala, but the muscular “vagina” 
of 7. novae-zelandiae, though leading directly to the uterus and oviduct, may represent 
it; and the teeth in its interior bear a striking resemblance to those in the bursa 
copulatrix of some of the Rhabdocoeles such as Proxenetes Habelhfer.”) But spines or 
teeth oceur round the mouth of the opening of the oviduet in Axine, Microcotyle 
and others. 
The testes resemble the compact type of these glands occeurring among the 
Rhabdocoela; but are also nearly approached in form by those of some ectoparasitic 
Trematodes, though there are no other members of the latter group that have four. 
The ovary has in many Rhabdocoeles the same form and relations and sometimes 
!) Untersuchungen zur vergleichenden Anatomie u. Histologie des Nervensystems der Platyelminthen, 
Mittheil. a. d. Zool. Station zu Neapel. II. Bd. p. 28. 
!) von Graf, Monographie der Turbellarien. Taf. VIII. fig. 16. 
