394 History of the Hairy-backed Animalcules. 



niiig forward along the sides. The mouth appears to me oval, 

 minute, slightly protrusile; Ehrenberg describes it as a tubo 

 furnished with eight teeth. It leads into a gullet with very 

 thick transparent walls, and a very slender perforation, which, 

 at about one-third the total length of the animal, enters a 

 straight intestine, of equal diameter with the gullet-wall. 

 This, as I have seen it, has been generally colourless, loosely 

 filled with irregular clear masses, and apparently terminating 

 at a curved transverse line, considerably above the fork. This 

 line is doubtless the outline of the swollen arched back, and 

 marks the position of the cloaca, which, as is frequently the 

 case, is visible only at the instant of its function. Ehrenberg 

 has induced the digestive organs to receive indigo. The same 

 observer has frequently seen ' a large developed egg contained 

 in the ovary, which occupies the arched cavity of the abdomen, 

 situate over (that is, more towards the back) the intestine. 

 The egg is about one-third as long as the whole animal. I 

 have seen the reproductive system in an inactive condition, 

 merely as clear, refracting viscera of large size, and irregular 

 shape, lying in the abdominal cavity, occasionally extending 

 forward to the neck. On one occasion I am pretty sure that 

 I saw, for a 'portion of its length, a tortuous ivater-vessel, run- 

 ning down one side. (See Fig. 3.) 



The movements of this little animal are smooth and grace- 

 ful, a sort of gliding or creeping over the water-plants ; rarely 

 swimming. Once I saw a Paramcecium come blundering 

 up against an unsuspecting Chcctonotus, who instantly doubled 

 his pace as if frightened, but soon recovered his equanimity. 

 Mr. Slack says, that among threads of conferva or decayed 

 vegetation, he has observed it grope about, and shake them 

 like a dog. (See Marvels of Pond Life, p. 84 ; where are two 

 excellent figures of the species, and somo interesting notes of 

 its manners.) 



Sp. 3. C. maximus {Mr.) (PI. i. Figs. 4 and 5). This is 

 about twice the size of the preceding, measuring from l-120th 

 to 1 -200th of an inch. The body is lengthened, slightly con- 

 stricted, with the head turgid and obtusely triangular; the 

 hairs on tho upper surface short and equal. Such is Ehren- 

 berg's definition of the species, who adds that the mouth is 

 furnished with about eight feeble teeth (possibly papillas). Tho 

 distribution of the bristles in one he observed in distinct longi- 

 tudinal rows; in another the arrangement appeared irregularly 

 diagonal. A single egg is developed at once, greatly dilating 

 the dorsal region of the abdomen, which Ehrenberg saw dis- 

 charged by tlic cloaca ;d)ovc the foot-fork; ho saw tho germ- 

 resicle dial inctly. 



Dr. Schulze suggests tho possibility that this species and 



