5o6 ORDER HOLOTRICHA. 



Genus I. COLEPS, Ehrenberg. 



Animalcules more or less evenly ovate, persistent in shape, cuticular 



surface usually longitudinally and transversely furrowed, and thus divided 



into numerous symmetrical quadrangular facets or interspaces ; the quad- 



ranf^ular facets smooth and indurated, the narrow intervening furrows soft 



and clothed with cilia ; oral aperture apical, terminal, surrounded with cilia, 



of slio-htly larger size than those of the general surface; anal aperture 



situated at the opposite or posterior extremity, the anterior and posterior 



margins usually mucronate. Dividing by transverse fission. Inhabiting 



salt and fresh water. 



The genus Coleps is usually cited as one of the few ciliate infusorial 

 groups whose members may be described as perfectly symmetrical ; many of the 

 representatives of the family of the Prorodontidae or Trachelophyllidae already 

 described possess, however, an equal claim to such distinction. The cuticular 

 ornamentation of the various species of the genus Cokps has been somewhat 

 diversely interpreted by independent observers. Perty and Dujardin maintained the 

 opinion that the quadrangular facets are indurated, and the narrow intervening 

 furrows soft and clad with cilia. Claparede and Lachmann, however, upheld the 

 view first expressed by Ehrenberg, to the effect that the furrows are indurated, and 

 fomi a continuous symmetrical trellis-work, and that the quadrangular facets are of 

 softer consistence and support the cilia. Having recently examined examples of the 

 typical species, Coleps hirti/s, with considerable care and the aid of the highest 

 available magnifying power, the present author unhesitatingly adopts the interpretation 

 of Dujardin and Perty. The facility and rapidity with which the animalcules of 

 this genus divide by transverse fission is of itself a point in favour of the view here 

 supported, for while the existence of a continuous trellis-like induration of the 

 cuticular surface would offer a considerable obstacle to such transverse division, 

 it takes place naturally and with the greatest ease along the line of one of the 

 previously existing and softer intersecting furrows. Diesing, on very insuflicient 

 grounds, has proposed to separate this genus into three, abandoning the original title 

 of Coleps altogether, and substituting in its place that of Pinacocoleps for C incurviis, 

 Cricocoleps for C. amphaeantJms , while all the rest, including C. hirtus and Stein's 

 Plagiopogon coleps^ are collated together under the generic name of Dictyocoleps. 

 The artificial character of such a plan of grouping is self-apparent. 



Coleps hirtus. PI. XXVII. Figs. 3 and 4. 



Body ovate, subcylindrical, more or less barrel-shaped, about twice as 

 long as broad, rounded posteriorly, slightly narrower and truncate in front ; 

 the anterior margin denticulate, three spinous processes or cusps developed 

 at the posterior extremity ; cuticular surface divided into quadrangular 

 areas and presenting a reticulate aspect ; endoplast spherical, subcentral ; 

 contractile vesicle single, posteriorly situated, colour whitish or light brown. 

 Length 1-500" to 1-400". 



Hab. — Pond water, among duckweed and Conferv(^, 



This widely distributed species is subject to some variation in contour and aspect. 

 One of these varieties having a more elongate outline lias received from Ehrenberg 

 the title of Coleps cloiigatus, and another, with green-tinted parenchyma, that of 

 C. viridis ; both, however, are now accepted as being merely local phases of the 

 present type. The active scavengering habits and voracity of Coleps hirtus have been 



