134 ON SOME NEW 



nearly twice the breadth. The peristome is thickened, but not 

 very prominent ; the endoplast is large, band-like, and curved. 

 When contracted, the zooids are nearly spherical. They are 

 grouped on a main rachis, which subdivides dichotomously with 

 great regularity. After the last main subdivision of the stems 

 there are generally two short stalks on the same side, and the ter- 

 minal one, each ending in a pair of almost sessile zooids. The 

 stems are broad and very finely ribbed transversely. These, and 

 all the zooids, are covered more or less thickly with a characteris- 

 tic flocculent coating, which was of a brown colour in this ditch. 

 The number of zooids in a colony varies from 3 or 4 to 80 or 90. 

 The larger colonies are very active and timid, frequently contract- 

 ing so as to form a ball at the top of the main rachis, and some- 

 times remaining thus for 24 hours. The small colonies remain 

 extended for long periods. The zooids very readily leave their 

 stems. Length of zooids, i-285th inch. Habitat, grasses and 

 roots of plants in slowly-running water. This species most nearly 

 resembles Z. dichotomum^ but it differs from this and from all 

 other species of the genus in the characteristic covering of floccu- 

 lent matter. The elongated shape of the zooids is also character- 

 istic. Contrary to the ordinary habits of the genus, I noticed in 

 the large colony mentioned above that one very long branch often 

 remained extended while the rest contracted, and this branch came 

 up into position last after contraction. I also saw one of the lower 

 branches contract independently, though the central fibrilla of the 

 stem is continuous throughout the colony. 



On Duckweed and other plants in the same ditch, I found a 

 new species of Fyxicola, which I propose to call Pyxicola 

 anfiulaia (PI. 15, Fig. 3). Lorica urceolate, nearly twice as long 

 as broad, constricted on one side below the oblique anterior 

 margin ; the side walls more or less undulated or ringed. These 

 undulations generally show two or three well-marked narrow 

 ridges, the lowest of which is about half way down the lorica, and 

 the two others are close above it. These are often much more 

 clearly seen on one side than on the other, and occasionally 

 they are difficult to see at all, or vanish altogether. The lower 

 half of the lorica has no ridges. In these respects this species 

 resembles P. socialis. The operculum is oval, and is surrounded 



