INFUSORIA FROM BRISTOL. 135 



by a thickened border ; under slight pressure the animal casts 

 off the operculum. The pedicle is colourless, transparent, and 

 short, about i-5th the length of the lorica. As in P. Carter i, 

 it is surmounted by a little boss-like prominence. Colour of the 

 lorica, chestnut brown ; yellow when young. The animal is thick, 

 fusiform, at times nearly cylindrical. It generally protrudes very 

 slightly from the anterior margin, its favourite position being with 

 the edge of the operculum resting obliquely on the margin of the 

 lorica, and the peristome completing the triangle. I have, how- 

 ever, seen it extended further, carrying the operculum some distance 

 above the lorica, and in a vertical position. The contractile vesi- 

 cle is large ; sometimes two or three are formed, which may or may 

 not coalesce before contracting. Length of lorica, i -400th inch ; 

 breadth, i -Sooth inch. 



In many respects this species is very like P. Carteri; the points 

 of difference are three. 



First, the dimensions are quite different, and the difference is 

 constant, as I have seen many specimens. The lorica of Carteri 

 is three times as long as it is broad, while this is not quite twice. 

 Secondly, the undulations of this species are much smaller than 

 those of Carteri, taking more the form of rings. Thirdly, the 

 rings are confined to the upper half of the lorica, while Cai-teri is 

 evenly undulated to the foot. The undulating outHne distinguishes 

 it from Affinis and Pusilla. The animal is hardy ; it lived com- 

 fortably for two months in a little corked tube, about an inch long. 



On the same weed I found a number of new species of Platy- 

 cola, which I have named P. bicolor, from the two colours of the 

 lorica. (PI. 15, Figs. 4, 5, 6, and 7). Lorica, dark yellow, oval, 

 much depressed ; length about i J times the breadth ; the yellow 

 portion of the lorica is obUquely truncated in front ; from it a deli- 

 cate, colourless neck rises to a height of about Ys the whole 

 length of the lorica, measured from the basal surface of at- 

 tachment of the lorica. The sides of the neck are straight, or 

 very slightly concave ; the upper side often nearly at right angles 

 to the axis of the body. This colourless neck is the first point of 

 interest in this species. De Fromentel describes a vaginicola, of 

 which the upper two-thirds are colourless and transparent, the 

 lower third brown. JMr. Kent thinks this so remarkable that he 



