704 ORDER PERITRICHA. 



Epistylis digitalis, Ehr. Pl. XXXVIII. Figs. 12-16. 



Bodies in extension elongate, cylindrical-campanulate, somewhat gib- 

 bous, from two or three to nearly four times as long as broad ; elongate- 

 pyriform, with an anterior nipple-like projection, when contracted ; the 

 frontal margin but slightly dilated, obliquely truncate ; ciliary disc consider- 

 ably elevated ; cuticular surface conspicuously striate transversely ; pedicle 

 thick, profusely and dlchotomously branched, coarsely and closely annulate, 

 secondary ramifications of the pedicle short, rarely equalling the length of 

 the extended zooids. Length of bodies 1-430" to 1-240" ; height of the 

 tree-like colony 1-16". 



Hab. — Fresh water, on various species of Cyclops and other Ento- 

 mostraca. 



This species is one of the most abundant representatives of the genus, being 

 rarely absent where Cyclops is plentiful, the limbs and carapace of this little Ento- 

 mostracon being often completely hidden beneath a perfect forest of its tree-like 

 colonies. Difficulty is sometimes experienced in separating this type from Epistylis 

 anastatica and E. galea previously described, but disappears on attention being 

 directed to the exceedingly distinct annulation of the entire pedicle and the elongate 

 and subcyhndrical shape of the extended zooids. The more usually somewhat 

 gibbous, anteriorly oblique truncate contour of the animalcules, as seen in profile, so 

 nearly resembles that of the flower of the foxglove. Digitalis, as to have suggested 

 the title conferred upon it by Ehrenberg. When first taken from its native pond it 

 is remarkable, unless carefully handled, how soon the zooids of this species develop 

 a posterior circlet of cilia and become detached from the parent tree, nothing but 

 the bare t^ngs of this last-named structure being frequently left within a few hours 

 from the time of their collection. The detached animalcules will, however, on such 

 occasions be found abundantly distributed in the water, swimming rapidly about, and, 

 as observed by the author, with the posterior extremity directed in advance, or 

 creeping over the surface of submerged objects, with the aid of the closely applied 

 basal region and supplementary ciliary girdle, after the manner of a Trichodina or 

 migrant Vortiaila. Left undisturbed, and with an abundant supply of water, for a 

 few days, many of these nomadic individuals find their way back to their previous 

 hosts, and commence severally the edification of a new family tree. At PI. XXXVIII. 

 Fig. 13 is given an illustration of an exceedingly attenuate variety of this species 

 observed on one occasion. In this instance the bodies of the extended zooids were 

 almost vermicular, their diameter in the centre scarcely exceeding twice that of the 

 supporting pedicle. 



Epistylis leucoa, Ehr. Pl. XXXIX. Fig. 4. 



Bodies broadly campanulate, convex anteriorly, somewhat gibbous ; 

 peristome-border dilated ; ciliary disc projecting in a dome-like manner ; 

 parenchyma transparent, cuticular surface smooth ; pedicle erect, thick, 

 smooth, solid, and articulate at the joints ; its branches very short, capitate ; 

 endoplasts band-like or S-shaped. Length of bodies 1-120"; of the entire 

 zoodendrium 1-24". Hab. — Fresh water. 



This species was obtained by Ehrenberg attached to the leaves of sedges in the 

 ponds of the Berlin Zoological Gardens, in January 1835, ice at the time covering the 

 surface of the water. In shape and size the zooids would appear to most closely re- 

 semble those qI E. plavicans var. dccumbens, but the ciliary disc is represented as much 

 more prominent ; the pedicle is also, in addition to being articulated, considerably 



