ROTATORLi. 



[ ^71 ] 



RUCKERIA. 



situated usually in the cervical region (PI. 

 43. lig. •■> ; PI. 44. fig-. 17), denominated the 

 calcar or respiratory tube, and terminated 

 by a retractile tuft of nou-vibratile cilia 

 (tig. 5 a). They have no relation, how- 

 ever, with this, Avhich corresponds to an 

 antenna. Huxley proved that they are 

 part of a water-system. 



Beneath the inteo-ument of the Rotato- 

 ria, a kind of irregular circulation, varying 

 with the motions of the body, or a simple 

 molecidar movement of minute granules, has 

 been noticed. These granules are probably 

 situated in the abdominal cavity ; in which 

 also sarcodic globules, sometimes free, at 

 others connected by filaments, have been 

 observed. 



Reproduction. — The Rotatoria are propa- 

 gated by means of sexual organs, and are 

 unisexual. The female organs consist of 

 one or two longer or shorter ovarian sacs or 

 ovaries, situated towards the posterior end 

 of the body in the abdominal cavity, the 

 oviduct terminating in the cloaca, or at a 

 distinct A-ulva. The ova are of an oval 

 foiTu, and are sometimes smooth externally 

 and soft. The -s^-inter-ova are larger and 

 darker than those hatched during the sum- 

 mer, and the outer coat is thick and hairy 

 or tubercular. The winter-ova which re- 

 main so long attached to the posterior part 

 of the body are probably gemmie ; they 

 sometimes remain adherent to the cloaca 

 for a time, and in a few instances they are 

 hatched Avithin the ovary. 



The testis is situated at the posterior 

 part of the body, and consists of a wedge- 

 shaped body, with a muscular duct opening 

 externally. 



Many of the Rotatoria are remarkably 

 tenacious of life ; and some of them are 

 stated to have revived after having been 

 kept dr}' for several years. 



Perfect desiccation destroys the Rotifers, 

 but they wiU last a long time with a very 

 slight amount of moisture. 



The families of the Rotatoria are thus 

 distinguished : — 



Ciliated margin of rotatory disk simple or continuous. 

 Margin entii'e. Solotrocha. 



Carapace absent Iclithydina. 



Carapace present • Qiciatina (?) . 



Margin undulate or excised. Schizotrocha. 



Carajiace absent Megalotrochsea. 



Carapace present Floscularieea . 



Rotatory disk divided or multiple. 

 Divided into several parts. Polyifocha. 



Carapace absent Hydatincea. 



Carapace present TiuchlauJdota. 



Divided into two parts. Zygotrocha . 



Carapace absent Philodinasa. 



Carapace present Erachionsea. 



See Albebtina. 



They are found wherever water exist% 

 provided it be not in a state of putrefaction, 

 — thus iu pools, on moist earth, mosses, in 

 gutters, &c., and even in the cells of mosses 

 and alga). 



BiBL. Ehr. Inf. ; Dujard. Inf. ; Siebold, 

 Verf/l. An. ; Dalrvmple, 'Phil. Tr. 1849, 331 j 

 Huxley, Mio: Trans. 1852, i. 1 ; William- 

 son, Micr. Jn. i. 1 ; Cohn, Siebold mid Kdl- 

 likers Zeitsch. vii. 431 ; Gosse, Tr. Micr. 

 Soc. iii. ; id. Ann. N. H. 1851, viii. 198 

 (several new genera and species) ; and 185G, 

 xviii. 333; Pritchard, /«/". ; Schmarda, Ncne 

 Rotatoria, 1861 ; Mecznikow, Sieh. und KoU. 

 Zts. 1865; Qu.Mic. Jn. 1666, 34 & 240; 

 Claparede, An. N. II. 1868, i. 309 ; Schloch, 

 Riiderthiere, 1869 ; Cubitt, M. M. In. vi. 

 168, viii. 5; Hudson, M. M. Jn. xiii. 45; 

 Pascoe, Zool. 



ROT'IPER, Cuv. — A genus of Rotatoria, 

 of the family Philodinjea. 



Char. Eyes two, situated upon the pro- 

 boscis ; foot furnished with lateral horn- 

 like processes, and with t\\o terminal toes, 

 giving its end a bifm-cate appearance; fresh- 

 water. 



R. vul(/aris (PI. 44. fig. 23). Body fusi- 

 form, white, gradually attenuated towards 

 the foot J length 1-48 to 1-24". 



This is one of the commonest of the 

 Rotatoria, and has long been linown as a 

 favourite microscopic object under the po- 

 pular name of the wheel-animalcule. The 

 anterior and upper part of the body termi- 

 nates in a proboscis, ciliated at the end, and 

 upon which the eyes are placed ; the two 

 rounded lobes of the rotatory organ are 

 placed laterally. Behind, and at the root 

 of the proboscis, is the calcar. 



In R. citrinus, the middle of the body is 

 yellowish, the horns of the foot long, and 

 the eyes round. In R. macrurus, the body 

 is suddenly narrowed into a long foot. lli 

 R. tardus the body is gradually attenuated, 

 but somewhat deeply constricted into seg- 

 ments. 



BiBL. Ehr. Lifus. 484 ; Pritchard, Inf. ; 

 Greuacher, M. Mic. Jn. 1870, 44. 



ROTIF'ERA, See Rotatoeia. 



RUBEFACTIOX of AVatek. See 

 Water. 



RUCKE'RIA. — A genus of Computitce. 

 The pericarp possesses HAUiS of an inter- 

 esting structui'e. 



