288 Characteristics of Rotifers. 



better.] " The cuirass composed of one or two pieces often 

 furnished with salient points, or appendages, either fixed or 

 moveable, and which do not change their shape when con- 

 tracted. The mouth, furnished with jaws, and preceded by 

 a vestibule, the ciliated walls of which are more or less pro- 

 longed into lobes garnished with vibratile cilia presenting the 

 aspect of toothed wheels in motion. Some tailless, others 

 having simple or bifurcate tails." 



We have to notice in this section the great variety of shape 

 from the common Brachion, or pitcher rotifer, which may be 

 roughly compared to a turtle in form, and which is furnished 

 with apowerful tail, that it lashes about like a cat, to the elongated 

 skeleton-like Dinocharis, or to Triarthra and Polyartlira, with 

 their remarkable appendages. In the greater part of this group 

 the cilia which give rise to the rotatory appearances are the 

 chief instruments of locomotion ; but those furnished with limb- 

 like appendages use them as locomotive organs in addition to 

 the cilia. Salpina is like a prismatic glass box ; Pteroclina like 

 a soup-plate, with a head and tail projecting at opposite sides; 

 and some of the others are very singular in aspect. 



We are now engaged merely in getting a general idea of 

 the whole group of rotifers, and pass from the Cuirassiers to 

 the Furcularians, who constitute a distinct family of Dujardin's 

 swimmers. He describes them as " animals with an ovoid 

 or cylindrical body, very contractile and variable in form, 

 covered with a flexible membranous tegument capable of 

 making folds in regular longitudinal and horizontal lines, with a 

 tail more or less long, and furnished with two fingers or styles." 

 This family contains, amongst others, the Notommata aurita, 

 or " eared" Notommata, so well described by Mr. Gosse, in 

 the "Transactions of the Microscopical Society" (May, 1850), 

 and which shows the water-vascular system and the muscular 

 system in a very striking way. The term " tail" must not 

 always be strictly understood, when speaking of rotifers. In 

 the case of the Notommata, for example, Mr. Gosse points 

 out that the so-called tail is a retractile foot with two pointed 

 toes. The chief conditions of belonging to Dujardin's Fur- 

 cularian family are, being swimmers, not haviug a rigid cara- 

 pace, and not being able to crawl as well as swim. The lowest 

 form of this family is almost worm-like (l/mdia torulosa). 

 Dujardin concludes his second order with the Alberticni family, 

 comprehending the still more worm-like Albertia, in which the 

 ciliary apparatus is feebly developed, and which is a parasite 

 in the intestines of earth-worms and snails. 



Dujardin's third order and sixth family include fche swim- 

 mers and crawlers, and comprehend the common rotifer and 

 other species which strongly resembles it. He describes 



