706 ORDER PERITRICHA. 



Epistylis invaginata, C. & L. PL. XXXIX. FIG. 18. 



Bodies of animalcules conical, thimble-shaped, one and a half times as 

 long as broad ; peristome-border widest, everted ; cuticular surface smooth ; 

 pedicle erect, unstriate ; secondary branches long and slender ; endoplast 

 ribbon-shaped, slightly curved, longitudinally disposed ; colonies comprising 

 but few zooids. Length of bodies 1-400". 



HAB. Fresh water, on aquatic insects. 



Claparede and Lachmann remark that the species most nearly resembling this type 

 is the E. branchiopyla as described by Stein, but from which it may be distinguished 

 by the more elongate form of the body, the smooth surface and even development of 

 the pedicle, and the longitudinal instead of transverse position of the endoplast. The 

 specific name conferred upon this type bears reference to the contour assumed by 

 the animalcule in its migrant or free-swimming state, the posterior extremity being 

 at such times invaginated or thrust into the substance of the body, in a manner 

 closely identical with that observed by the author under similar conditions of Vorti- 

 cella striata. The examples of this species examined by its discoverers were found 

 attached to the abdominal segments of the larvse of a Hydrophihis. 



Epistylis timbilicata, C. & L. PL. XXXVIII. FIG. 9. 



Bodies ovoid, narrowest and slightly constricted anteriorly ; the peri- 

 stome-border not dilated ; ciliary disc produced centrally in the form of an 

 umbilicus; pedicle thick, short, smooth, and evenly branched, its total 

 height scarcely exceeding that of an expanded zooid. Length of extended 

 bodies 1-400." 



HAB. Fresh water, on the larvae of the common gnat, Culex pipiens, 

 forming colonies of but few zooids. 



Although not mentioned by Claparede and Lachmann in their descriptive text, 

 their drawing given of the species represents the surface of the integument as finely 

 striate transversely. D'Udekem * has since obtained this variety from the neighbour- 

 hood of Brussels, his illustration of an adult colony-stock being here reproduced. 

 In their contracted state, according to this observer, the zooids become plicate 

 posteriorly, while the anterior region is produced in a snout-like manner. 



Epistylis coarctata, C. & L. PL. XXXVIII. FIGS. 10 AND u. 



Bodies ovato-fusiform, a little over twice as long as broad, inflated 

 centrally, tapering subequally towards both the anterior and the pos- 

 terior extremities ; cuticular surface smooth ; peristome-border very narrow 

 and contracted ; endoplast band-like, curved, transversely placed ; pedicle 

 sinuous, very slender, smooth, sparingly branched, secondary ramifications 

 supporting the zooids usually very short. Length of bodies 1-500". 



HAB. On Mollusca and vegetable debris from pond and sometimes 

 stagnant water, in the neighbourhood of Berlin (C. & L.). Colonies small, 

 consisting usually of but three or four animalcules. 



This very graceful type is distinguished by its slender, fusiform contour, and 

 exceedingly narrow peristome, in both of which respects it would appear to 

 somewhat resemble the Opercularia stenostomata of Stein. From this last-named 



* 'Infusoires de la Belgiqne," 1864. 



