106 THE ROTIFEBA. 



animal when rotating, is very observable, as are also its stiffness, and yet great mobility, 

 as well as its unusual number of joints. Nor are the actions of this organ less peculiar, 

 for, in a manner of which I have met with no other example in the class, the animal, in 

 the act of protruding, jerks the antenna from side to side as if feeling with it, wags it 

 about rapidly but not vibratingly, and often taps the water, as it were, with it. As soon 

 as the wheels are quite expanded the antenna becomes still. The organ is very slightly 

 fusiform, quite transparent, and has either a tube or a band running throughout its 

 middle, connected apparently with three very short bristles which project from the some- 

 what enlarged truncate extremity. Perhaps these are very sensitive, and the band may 

 be a nervous thread which conveys impressions to the brain. Indeed, by careful focus- 

 ing with a high power, the medial bristle (viewed dorsally) is seen to have a sensible 

 diameter, and to be the continuation of the permeating band projected. Within the 

 first joint, about one-third from the base, the part exterior to it can be retracted. 

 There is not the least bending at these joints ; the wagging is solely from the base. Two 

 small pale-crimson eyes are low down in the column, which is normal in form. An 

 ovate body may sometimes be seen so large as almost wholly to occupy the greater 

 moiety of the abdominal cavity, quite transparent and colourless, in the midst of which 

 is a great mastax, not to be distinguished, even in dimensions, from that one which is 

 proper to the animal, but motionless. 1 This of course indicates an unborn young, and 

 proves this species to be viviparous. Alongside of this embryo lies a large sac, 

 doubtless the stomach, throughout which the action of vibratile cilia lining the interior 

 is clearly visible. The foot, spurs, and toes are of the usual form. These lowest 

 joints are usually shortened ; the animal habitually sitting, when at rest as well as 

 when rotating, in a squat position, so that they are almost, if not quite, concealed, the 

 long antenna always projected. Generally, save when distended either by digesting 

 food or by an advanced embryo, the whole body is marked with lines, which are longi- 

 tudinal folds of the skin, not greatly interfering with vision. The corona is unusually 

 large and the wheels more than usually circular ; the latter are separated dorsally by a 

 wide sulcus, the lower edge of which is a straight horizontal line. The mallei are 

 evidently two-toothed. P.H.G.] 



Dr. Bartsch found this species in the Weilheimer pool, near Tiibingen, in company 

 with Floscularia and Mclicerta, and published an account of it (loc. cit.) in 1870. He 

 describes the great length of the antenna and the creature's curious actions, " stretching 

 its long antenna far forward and moving it up and down as the water-wagtail does its 

 tail " ; and, under the impression that it was a new species, named it R. Motacilla. I 

 have met with this species several times in the clear water of Abbot's pond near 

 Clifton. It was always snugly ensconced in a floccose heap on a stem of alga, 

 or in the axil of a water plant ; and its presence was usually first betrayed by its 

 long antenna, which could be seen waggling about some time before the animal itself 

 appeared. 



Dr. Bartsch in " Eot. Hungari " (loc. cit.) figures the gastric glands, stomach, ovary, 

 and contractile vesicle. 



Length, ^^ inch (P.H.G.) Habitat. Near London; Woolston, near Birmingham; 

 Stormont Loch (P.H.G.) ; Clifton (C.T.H.) : not common. 



R. HAPTICUS, Gosse, sp. nov. 

 (PL X. fig. 3.) 



[SP. CH. Body clear, brotvn-stained, not strongly plicate, not enveloped in mucus ; 

 antenna long, stout, motionless when extended ; corona small. 



1 I belic,ve that I have seen the distinction between the stomach and the intestine ; and also 

 another great viscus, which must be the ovary. The oesophagus is wide and short. After some hours, 

 the mastax of the embryo worked ; but not rapidly, and only at intervals. P.H.G. 



