GENUS CYCLOTRICHA-TRICHODA. 535 



Genus III. CYCLOTRICHA, S. K. 



Animalcules free-swimming, more or less ovate, persistent in shape, 

 entirely ciliate ; oral aperture ventral, situated at the bottom of a pocket- 

 shaped oral fossa, the entrance to which is surrounded by a simple and 

 entire circlet of cilia, larger than those of the general cuticular surface, 

 the further confines of oral fossa supporting a watchglass-shaped undulating 

 membrane. 



This genus is herewith established for the reception of the Ophryoglena citreum 

 of Clapar^de and Lachmann. From Ophryogh-na and Mcniscoskvnum it is to be 

 distinguished by the larger calibre of the oral cilia, in comparison widi those of the 

 general surface ; their simply circular disposition serves at the same time to separate 

 it from Pamphrys, 



Cyclotricha citrea, C. & L. sp. Pl. XXVI. Figs. 67 and 68. 



Body lemon-shaped, pointed at each extremity, about one and a quarter 

 times as long as broad ; the entrance to the oral fossa situated at a distance 

 of one-quarter of the total length from the anterior extremity of the body ; 

 the adoral cilia forming a simple circular fringe ; no pigment-spot or tricho- 

 cysts ; endoplast elongate, band-like ; contractile vesicle single, spherical, 

 located near the dorsal margin. Length of body 1-225". 



Hab. — Bog water. 



Genus IV. TRICHODA, Mailer. 



Animalcules free-swimming, elastic, but more or less persistent in shape, 

 ovate or pyriform ; oral aperture situated at the pointed and obliquely 

 truncate anterior extremity, approached by an ovate oral fossa, whose 

 inner wall gives attachment to a single, vibratile, flap-like membrane ; 

 cuticular surface finely ciliate throughout, a circlet of larger cilia sur- 

 rounding the entrance to the oral fossa. Especially abundant in j^utrid 

 infusions. 



The animalcules of this genus, while corresponding closely in external contour 

 and habits with those of Ettchelys, are to be distinguished from them by the presence 

 of the minute vibratile membrane that is enclosed within the oral fossa. Trichoda, in 

 common with Eiichclys, was originally distinguished by Ehrenberg with reference to 

 the apparent absence of cilia throughout the general surface of the cuticle. Fine 

 body cilia are now known to exist in all the species. 



Trichoda pura, Ehr. Pl. XXVII. Fig. 47. 



Body elongate-pyriform or clavate, slightly curved towards the ventral 

 aspect, about three times as long as broad, widest and rounded posteriorly, 

 tapering gradually towards the anterior extremity; oral fringe of cilia alone 

 conspicuous, those of the general cuticular surface very fine ; endoplast 

 spherical, subcentral ; contractile vesicle posteriorly located. Length 

 1-720". 



