6Q(5 SYSTEMATIC HISTORY OF THE INFUSORIA. 



six clefts. In some genera the cilia of this organ are quiescent at intervals, 

 not vibrating continuously ; the alimentary canal is complex, usually divided 

 transversely into several segments, and with various external appendages, 

 believed to be glandular, the proventricular segment, gizzard, or pharyngeal 

 bulb furnished with teeth. Lacinularia has a mouth, oesophagus, pharyngeal 

 bulb with teeth, a stomach constricted into three segments, and a short 

 intestine ; the lower stomach clothed internally with a very long ciha. 

 Melicerta has a similar arrangement, but with only two unequal segments in 

 the stomach, both of which are ciliated interiorly. Two water-vascular 

 canals arise from a contractile sac opening into the cloaca, and pass upwards, 

 one on each side of the alimentary canal to the head, where, in Lacinularia , 

 they ramify into a network ; along their course they have appended to them 

 small tags or sacs, each containing a large vibratile cilium. These have been 

 seen in Lacinularia, Melicerta, and Stephanoceros. In Lacinularia, Limnias, 

 and Melicerta, a small lobate mass exists near the mouth, believed by Huxley 

 to be a cerebral ganglion. Leydig assigns nervous functions to small bodies 

 distributed through Lacinularia ; but these appear to be merely the smaU 

 stellate masses of viscid protoplasm described by WiUiamson in Melicerta, 

 and Leydig in Stephanoceros. Eyes exist in all the genera, except Tuhico- 

 laria, at some stage of life. In Melicerta and Lacinularia they disappear as 

 the animal approaches adult life. Gosse says that the same is usually the 

 case in Floscularia, but that he has occasionally met with adult specimens in 

 which eyes were present. Some species (if not all) have well-marked fasciculi 

 of voluntary muscular fibre, especially running parallel to the long axis of 

 the body, which their contraction shortens. Male reproductive organs hitherto 

 unobserved. Female organs an ovisac composed of thin transparent mem- 

 brane, distended with granular protoplasm, in which are distributed cells or 

 germinal vesicles, each containing a nucleus or germinal spot. In Melicerta 

 this ovarium communicates with the cloaca by means of an oviduct. Some 

 species produce two classes of eggs, one being probably the true o\Tim, the 

 other an encased gemma or bud. Several species retain the eggs within the 

 envelope of the parent until the young are hatched ; others set them free at 

 an early stage of embryonic development. 



Ehrenberg's arrangement of the genera of this family wUl be found at 

 p. 478 of the General History. 



Eyes present Tubicolaria. 



One eye present (when young) Stephanoceros. 



/Envelope of the single animal- 1 Limnias. 



^ , ^ , J cules distinct or separated... J Cephalosiphon. 



Eotary organ two-parted ! ^ j r r- 



when fuU-grown , ^ ,„p, „f y,, ,; , ,„i^,,. , ^.^^^^ 



\ cules conglomerated J 



Eotary organ four-parted when full grown Melicerta. 



i^ Rotary organ five- to six-parted when full-grown Floscularia. 



Two eyes 

 present 

 (when j 

 young) 



Dujardin has a family of " Flosculariens," which, however, differs much 

 from that of Ehrenberg, both in its distinctive characters and in the species 

 assigned to it. The French naturalist includes only two genera, viz. Flos- 

 cularia and Stephanoceros. Contrary to Ehrenberg's assertion, these two 

 genera are stated by Dujardin to be destitute of a rotary organ, and indeed 

 of vibratile cilia, and are described as ha\dng a campanulatc, contractile 



