NOTOMMATAD A. ig) 
whom I have received many specimens—a lady, who, for many years, has given intelli- 
gent attention to this class of animals, and who has aided me very effectively in my 
researches.—P.H.G.]! 
Length, +}, to 45 inch. Habitat. Pools near Birmingham (C.T.H.); Cheltenham 
(P.H.G.): not rare. 

Genus PLEUROTROCHA, Ehrenberg. 
GEN. CH. ‘“ No eyes; mallei one-toothed ; foot furcate’’ (EHhr.). 
[There seems nothing very obvious to distinguish this genus from Notommata, but 
the lack of eyes, both cervical and frontal; and characters that are merely negative are 
always somewhat unsatisfactory. The form seems scarcely to have attracted attention 
in Britain. In the close, almost daily, study of the class, which I pursued some thirty 
years ago, it never occurred to my notice; no example of it appears in Dr. Collins’s 
richly-stored book of drawings ; Dr. Hudson has no record of it ; and in my recent resump- 
tion of the study, extending over the last year and more, I have met with but three 
examples; which, with more or less certainty, I identify with the three recorded species 
of Prof. Ehrenberg. Doubtless, by us all, it may possibly have been confounded with 
the obscurer species of Notommatade, and have been overlooked. But yet the common 
difficulty of discerning the eye in a restless animalcule is more likely to cause a Notom- 
mata to be taken for a Pleurotrocha, than a Pleurotrocha for a Notommata.—P.H.G.] 
P. constricta, (?) Ehrenberg. 
(Pl. XVIII. fig. 3.) 
(SP. CH. Toes moderately long, acute, straight. 
If this is identical with P. constricta, the singular and almost unprecedented illustra- 
tion which Prof. Ehrenberg has given us on the testimony of his own eyes, of its preda- 
tory instincts, I may cite as adding to it the greatest interest. He has figured the ap- 
parently weak and unarmed Plewrotrocha as watching a specimen of the swift and vigorous 
Notommata lacinulata; then, as having seized it; then, as sucking out its juices ; and 
then, as having dropped away the now empty skin. Well may he give it the secondary 
title of The Robber. 
I have seen nothing of this in the little delicate creature which I here represent. It 
oceurred to me in the spring of 1885, and then for so brief a period that I had but just 
time to make a drawing of it, which is here reproduced. It is indubitably rare. Ehren- 
berg appears to have seen but two examples, one of which was the above warrior of now 
historic renown. I had no time for measuring mine, but his length of +}; inch would 
well enough agree with my estimate. But, a few months later, I met with a specimen 
in water from Dundee represented in fig. 8, which I conclude to be specifically identical 
with the above, though there are some slight differences. The front is broader; and, 
though I could not say that auricles were actually protruded, their presence seemed 
indicated. (I incline to think the existence of these aids to locomotion more usual in the 
class than is generally accredited.) The toes also are more slender and more acute. 
It was active and moderately swift, gliding through the clear water; now and then 
suddenly darting a little right or left of its course, and apparently seizing some invisible 
prey. ‘The manner of the action could not be mistaken ; it was manifestly predatory. 
The mastax was large and conspicuous; but I could not obtain a look at it suffici- 
ently steady to define it. The intestinal canal was ample and filled with dark bistre- 
' In one specimen I observed, on a side view, a long egg-shaped contractile vesicle lying between 
the hind end of the stomach and the ventral surface, and terminating in a delicate tube entering the 
cloaca. The vesicle filled and emptied eyery 24 seconds.— C.T.H. 
e2 
