new Infusoria from American Fresh Waters. 443 



the Lagynus of Quennerstedt, in which the pharynx is plicate 

 and the apical groove wanting - . The movements of the infu- 

 sorian are rapid and usually by rotation on the long axis. 



Colpidium truncation, sp. nov. (PL XV. fig. 13.) 



Body somewhat reniform, from two to three times as long- 

 as wide, striate longitudinally, compressed anteriorly, the 

 extremities subequal in width, the posterior one evenly 

 rounded, the anterior somewhat curved toward the ventral 

 aspect, the frontal border obliquely truncate ; oral aperture 

 ovate, the pharynx long ; vibratile membrane large, conspi- 

 cuous ; contractile vesicle single, located on the right-hand 

 border of the posterior extremity near the dorsal surface ; 

 nucleus ovate or subspherical, single, subcentral; anal aper- 

 ture postero-terminal. Length of body 5-^j to $$-$ inch. 



Bab. Standing water, with Myriophyllum and other aquatic 

 plants. 



This form was for a time very abundant in a small vessel of 

 water from an aquarium containing Myriophyllum in various 

 stages of growth and decay. It differs from the hitherto 

 single-known member of the genus in the oblique truncation 

 of the frontal border, the single nucleus, and the position of 

 the contractile vesicle. In numerous instances conjugation 

 was observed, union taking place between the anterior third 

 of the ventral surface of each animalcule. Transverse fission 

 was also repeatedly noticed, the newly-separated animalcules 

 being subspherical in form, soon, however, assuming the nor- 

 mal contour of the adult infusorian. 



Vorticella octava, sp. nov. (PL XV. fig. 17.) 



Body conical- campanulate, somewhat changeable in form, 

 once and one half to twice as long as broad, tapering poste- 

 riorly, slightly constricted beneath the peristome, which is 

 revolute and exceeds the body-centre in width ; obovate or 

 pyriform when contracted ; cuticular surface finely striate 

 transversely ; ciliary disk somewhat and obliquely elevated ; 

 pedicle seven to nine times as long as the body, the hyaline 

 sheath apparently thickened on one margin and twisted about 

 the stout muscular thread ; contractile vesicle single. Length 

 of body gig- to TlI Vo- inch. 



Nab. Standing water ; attached to Proserpinaca. Solitary 

 or few together. 



This is not uncommon in the pond where it was originally 

 found, and the peculiar appearance of the sheath about the 

 pedicle seems to be characteristic of the species ; in none of 



