NOTOMMATAD2E. 21 



developed, and opaque with chalk deposits. This genus may retain the name of Notom- 

 mata. There still remain a multitude of species, mostly of small, none of large, size, with 

 characters mainly negative, yet having much in common with each other, a community 

 more easily recognized than described ; but having the ciliate face more or less obliquely 

 prone. These make the genus Proales. The second of these three is characterized above, 

 and shall still prolong the time-honoured title. It is even now a populous tribe, as 

 usual with typical groups : yet not unnaturally associated. Its constituent species are 

 easy of recognition, by three prominent characters, all fairly constant 1, the tail ; 2, the 

 auricles ; 8, the opaque brain. The first is moderately conspicuous, and readily dis- 

 tinguished by being always on the dorsal side of the cloaca, while the foot and toea are 

 always 011 the ventral. The second is not always available, being often inactive and 

 invisible ; but if seen, seen without doubt. The third is the best mark : the opaque 

 brain-mass, like a vast well-defined black cloud, striking the eye at the first glance, 

 unmistakably. 



The genus is widely distributed in our fresh waters. P.H.G.] 



N. AUBITA, Ehrenberg. 

 (PL XVII. fig. 6.) 



Notommata aurita .... Ehrenberg, Die Infus. 1838, p. 430, Taf. lii. fig. iii. 



,, Gosse, Trans. Micr. Soc, Lond. 1852, p. 93, pis. xii. xv. 



[SP. CH. Body sub-cylindric, ventricose ; brain opaque ; head wide, furnished with 

 evertile auricles ; tail minute. 



Of this moderately large species, of elaborate organization, and of frequent occur- 

 rence, the anatomy has been given with so much detail, by myself (loc. cit. supra), that 

 only a very succinct account is needful here. Its opaque brain-mass, looking like a great 

 black ball in the neck, connected by a tube with the front, renders it conspicuous as 

 soon as it is seen ; and when it glides through the clear water, the sudden quickening of 

 its speed, as it everts the great ciliate hemispheres from its two cheeks is hardly less 

 notable. 1 The foot consists of two very short and small joints, telescopically infolded ; 

 bearing two furcate toes, acute cones, also short and small. P.H.G.] 



Length, ^ to T ^ inch. Habitat. Fresh waters. Common everywhere (P.H.G.). 



N. ANSATA, Ehrenberg. 

 (PI. XVII. fig. 3.) 



[SP. CH. Closely resembling N. aurita inform and structure, but smaller ; the brain 

 not opaque ; the toes long. 



The examples of this species that I have observed I could distinguish from the pre- 

 ceding only by the points mentioned above. Perhaps it is slightly more slender, more 

 cylindrical. Ehrenberg gives no appreciable diagnosis between the two forms ; nor can 

 his figures be distinguished, save by the lack of opacity on the brain of ansata. The 

 length of the toes is, however, a good mark, and readily observed. * 



A few specimens have occurred to me in water sent me by Dr. Collins from Berkshire, 

 containing aquatic moss. They moved in the clear, with great impetuosity, driving 

 round and round, and turning on their course, with no apparent aim. One made its 

 way just within the edge of a moss-leaf, where it worked for itself a little hollow, in 

 which it remained several hours, incessantly turning round and round, or to and fro, as 

 fast as it could move, without a moment's intermission. In this example the alimen- 



1 Herr Eckstein (Sieb. u. KQll. Zeits. 1883, p. 361) describes in this, as in many other Rotifera, 

 specks of crimson pigment near the front, each in connection with a setigerous sense-organ. He con- 

 cludes these to be secondary eyes. I have myself never detected them; neither has Dr. Hudson, nor 

 Dr. Plate. 



