Maskell. — On Freshwater Infusoria. 55 



an exceedingly long filiform neck, often reaching six or 

 seven times the length of the body, and terminating in an 

 obtuse sub-conical region rather wider than the neck, with 

 a circle of longer cilia beneath it. Contractile vesicle single, 

 posterior : endoplast elliptical, sub-lateral. The whole body 

 and neck are marked with a network of striffi. 



Length when fully extended reaching perhaps -^ inch = 

 357 fji, but the twistings and curlings of the thread-like neck 

 are so rapid that measurement is very difficult. 



Wellington, W. F. Barraud. 



Closely allied to T. olor, Miiller, but differing in the 

 position of the single contractile vesicle and the character 

 of the nucleus. 



Genus Amphileptus. 

 Amphileptus anser, Ehrenberg. Wellington. 



Genus Colpidium. 

 Colpidiiim cucullus, Schrank. Wellington. 



Genus Plagiopyla. 

 Plagiopyla varians, sp. nov. Plate IV., fig 7 ; a, b. 



Animalcules free- swimming ; motion rapid, gliding ; per- 

 sistent in shape, sub-reniform. Oral fossa ventral, a little in 

 advance of the median line, sometimes shallow, broad, and at 

 right angles to the axis of the body, sometimes tubular, conical 

 and oblique ; containing a narrow vibratile membrane which 

 does not quite reach to the aperture. Nucleus posteriorly 

 located, conspicuous, circular. Contractile vesicles 2, placed 

 between the oral fossa and the posterior extremity. 



Length, ^ig inch = 125 fx. 



Wellington, W. M. Maskell. 



Eesembling P. nasuta, Stein, but differs m the position of 

 the nucleus, the two contractile vesicles, and the variation of the 

 oral fossa. The animalcules observed presented this variable 

 arrangement in a large number of specimens, and were at first 

 thought to be distinct ; but on further consideration they seemed 

 to be really the same. 



Genus Pleuronema, 



Pleuronema coronata, Kent. Wainui. 



This animalcule appears to be identical with Kent's infu- 

 sorian in everything except size. The European species is 

 stated to have a length of only ^'^ inch = 86 /x, whilst the 

 Wainui specimens reached -j^ inch = 125 |/. It is not P. 

 chrysalis, as it possesses long, fine, rigid setae in addition to the 

 cilia. 



