Huxley on Lacinularia socialis, 5 
lular cceca projecting from its outer surface. Within it is 
clothed with very long cilia. 
The intestine is short and wide, and comparatively delicate ; 
it bends suddenly upwards on the side opposite the mouth, 
and terminates in a cleft of the integument, whose whole extent 
it did not seem to me to occupy. (Fig. 1 k) 
The Water Vascular System. — This system is thus loosely 
and confusedly alluded to — I cannot call it described — by 
Professor Ehrenberg :* — " The vascular system consists of 
transverse circular canals in the body, a vascular network at 
the base of the wheel-organ, with perhaps a broad circular 
canal at this part, and of trembling gill-like bodies" — (loc. cit., 
p. 403). The vascular system is so obvious,t that it is diffi- 
cult to understand how it can have been thus blurred over. 
The reader will bear in mind that the two bands which run 
up from the cloaca in many Rotifera, and are usually con- 
nected at their extremity with a " contractile vesicle," while 
they give attachment in their length to the " trembling gill- 
like organs" of Ehrenberg, are considered by the latter to be 
the testes. He says that " the trembling organs " appear to 
be within the sac in Hydatina, outside it in Notommata. 
Von Siebold (' Vergleichende Anatomic ') first pointed out 
that a vessel runs up in each of these bands, and that the 
" trembling organs " are short branches of these vessels, each 
of which contains a vibrating ciliary band (Flimmer-lappchen), 
to which the trembling appearance is due. According to Von 
Siebold each of these vibrating bodies indicates an opening in 
the vessel. 
Oskar Schmidt (' Versuch einer Darstellung d. Organisation 
d. Raderthiere' — Erichsons Archiv, 1846) asserts that the 
ends of the water-vessels are closed, and that the vibrating 
body is within them. 
Dairy mple (loc. cit.) saw no testes in the lateral bands of 
Notommata^ and considers that the " tags" (the " trembling 
organs " of Ehrenberg) are externally ciliated at their extre- 
mities. 
Mr. Gosse (' Microscopical Transactions,' 1851) describes 
the water-vascular system in Notommata aurita^ and states 
that the " tags " of Ehrenberg are really pyriform sacs ; but 
he seems not to have distinguished the contained cilium, at 
least his description is ambiguous. " When trembling m.ode- 
rately they are seen to be little oval bags attached to the tor- 
tuous vessel by a neck and sac at the other end. A spiral 
* "I can tlms affirm, that what Ehrenberg describes as vessels in 
Lacinularia are in fact not vessels at all." — Ley dig, loc. cit., p. 463. 
t " Selir ans-gepragt," Leydig, p. 465. 
