NOTOMMATAD.E. 10 



whom I have received many specimens — a lady, who, for many years, has given intelh- 

 gent attention to this class of animals, and who has aided me very effectively m my 

 researches. — P.H.G.] ' 



Length, yijy to -^fg^ inch. Habitat. Pools near Birmingham (C.T.H.) ; Cheltenham 

 (P.H.G.): not rare. /JD-^ 



Genus PLEUEOTROCHA, Ehrenberg. 



GEN. CH. "A'oeyes; mallei one-toothed ; toot furcate" (Ehr.). 



[There seems uothmg very ob%-ious to distingmsh 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 ^vith the three recorded species 

 of Prof. Ehrenberg. Doubtless, by us all, it may possibly have been confounded with 

 the obscurer species oi Kotommatada, and have been overlooked. But yet the common 

 difliculty 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 XotomiTiata. — P.H.G.] 



P. coNSTRicTA, I?) Ehrenberg. 

 (PI. XYIII. fig. 3.) 



[SP. CH. Toes vioderatehj 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 PleurotrocJm as watching a specimen of the swift and \-igorou3 

 N'otommata 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 Bobber. 



I have seen nothing of this in the little delicate creature which I here represent. It 

 occurred to me in the spring of 1885, and then for so brief a period that I had but just 

 time to make a dra^^•ing 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 j^ 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 httle 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 every 2it seconds.— C.T.H. 



c 2 



