504 ORDER HOLOTRICHA. 



extending backwards to about one-third of the length of the body, its walls 

 plicate longitudinally, the anterior border projecting slightly beyond the 

 front margin of the body ; contractile vesicle single, spherical or rosette 

 shaped, situated posteriorly, close to the anal aperture ; endoplast band-like, 

 sinuous ; cuticular surface longitudinally striate ; cilia very short and fine- 

 Length of body 1-125". Hab.— Bog water: Berlin (C. & L.). 



The contractile vesicle of this species has been showTi by both Claparede and 

 Wrzesniowski to exhibit phenomena closely corresponding with what has been 

 already described of TraJtelophylhim apiadatum, a portion of the accumulated 

 fluid being driven at the time of systole into minute rounded sinuses, the contents 

 of which afterwards coalesce together, and, increasing in volume, present all the 

 characteristics of the preceding vacuole. These metamorphic phenomena exhibited 

 by the contractile vesicle in Trachdophylltim and Enchdyodon, are directly com- 

 parable with the stellate modifications of this same structure already recorded of the 

 two genera Paramecium and Otostoma. 



As shown by Wrzesniowski, a minute pore or aperture places the central lacuna 

 of the contractile vesicle of Enchelyodon farctus in direct communication with the 

 outer water. The aspect of this vesicle, in its fully dilated rosette-shaped condition, 

 showing its central pore-like aperture, is reproduced from Wrzesniowski's delineations 

 at PI. XXVr. Fig. S3. 



Enchelyodon elongatus, C. & L. Pl. XXXII. Fig. 17. 



Body attenuate, clavate, four or five times as long as broad, the anterior 

 half narrowest ; pharynx simple, short, and tubular ; contractile vesicle 

 single, spherical, posteriorly located ; endoplast central, oval ; cilia fine, 

 short, and evenly distributed. Length unrecorded. 



Hab. — Salt water : Norwegian coast (C. & L.). 



Although not mentioned in the description, Lachmann's figure of this species 

 indicates the presence of several symmetrically placed reflected sets, four on each 

 side, at the anterior extremity or oral region of the body. Should these setae 

 really exist, this form would seem to demand a generic title separate from that of 

 Enchelyodon for its reception. 



Genus III. UROTRICHA, C. & L. 



Animalcules free-swimming, ovate or elliptical, entirely ciliate, motion 

 of cilia irregular and independent; oral aperture apical, terminal, a single 

 long, projecting springing-hair or seta developed at the posterior extremity. 

 Inhabiting fresh water. 



The motion of the cilia in the representatives of this genus is peculiar, and 

 serves at a glance to distinguish them from those of the ordinary Holotrichous 

 types. Instead of vibrating in rhythmical cadence, each cilium waves in- 

 dependently and apparently without any order, the ciliary system as a whole 

 consequently assuming a comparatively irregular and untidy aspect. In creating 

 the genus Urotridia, Claparede and Lachmann remark that Professor Johannes 

 Miiller had indicated the possible identity of their Urotridia farda with the 

 Pantotridiutn lageiiida of Ehrenberg. M. Lieberkuhn, however, has supported 

 them in regarding the two forms as separate. Having frequently encountered the 

 animalcule described by Ehrenberg under the last-named tide, the author is likewise 

 enabled to establish its distinctness from the species introduced by the Genevan 

 authorities, though it is obviously desirable to refer it to the same generic group. 

 The original genus Paiitotridmm of Ehrenberg includes, in addition to P. lagemila, 



