GENUS EPISTYLIS. 707 



species its describers report it as differing in its larger size, and in the more slender 

 and attenuate proportions of the secondary pedicles, which while short are never so 

 abridged as to impart to the bodies that sessile aspect which characterizes Stein's 

 species. The author refers without hesitation to Claparede and Lachmann's type 

 the unnamed Epistylis figured by Mr. H. J. Slack, in his ' Marvels of Pond-life,' 

 p. 95, 1861. The group there delineated, and reproduced at PI. XXXVIII. Fig. n, 

 would appear to be a remarkably luxuriant example, the branching pedicle support- 

 ing no less than seven zooids in place of the three, or four at most, only observed 

 by its original discoverers. 



Epistylis tubificis, D'Udk. PL. XXXIX. FIGS. 7 AND 8. 



Bodies subcylindrical, thimble-shaped, about twice as long as broad, the 

 frontal margin truncate, widest, moderately dilated, the posterior extremity 

 rounded and slightly tapering ; pendulous, and irregularly plicate trans- 

 versely when contracted ; pedicle short, slender, smooth, and transparent, 

 branching dichotomously ; basal stem scarcely equalling the length of an 

 extended zooid and each successive ramification decreasing in length ; entire 

 colony-stock comprising six or eight zooids only. Length of bodies 1-250". 



HAB. Fresh water, on Tubifex rivulorum. 



Among the figures given of this species D'Udekem represents an animalcule 

 having the posterior portion of its body extended in an irregularly lobate manner 

 (see PI. XXXIX. Fig. 8), and which may perhaps be interpreted as a semi- 

 amoeboid phase, analogous to that prevalent among the Flagellata previous to 

 entering upon an encysted state. In their contracted condition the zooids assume 

 a reflected or pendulous posture closely resembling that of Opercularia nutans. 



Epistylis pyriformis, D'Udk. 



Bodies when extended, subfusiform, rather over twice as long as broad, 

 narrowest posteriorly, the cuticular surface smooth ; pyriform, with several 

 transverse posterior plications, when contracted ; peristomal border slightly 

 everted ; ciliary disc elevated but a small way above its margin ; pedicle 

 moderately stout, smooth and transparent, forming short, regular, widely 

 divergent dichotomous branchlets, neither these nor the main stem equalling 

 in length an extended animalcule. Colonies small, including five or six 

 zooids only. Length of body 1-250". 



HAB. Pond water, on the larvae of Tipula, mostly attached to the 

 posterior extremity. 



Excepting for the more fusiform contour of the zooids, and the normal posture 

 maintained by them when contracted, this species may be readily confounded with 

 the one previously described. 



Epistylis articulata, From. PL. XXXIX. FIG. 3. 



Bodies elongate-conical, tapering posteriorly, somewhat gibbous, nearly 

 three times as long as broad ; cuticular surface smooth ; peristome-border 

 slightly dilated ; ciliary disc moderately elevated ; vestibular seta con- 

 spicuously developed; pedicle dichotomous, short, stout, and sparingly 



R 2 



