98 NATURAL HISTORY 



clear water, and often along with the Cercaria viridis, 

 A magnifying power of 200 is sufficient for their exa- 

 mination. 



166. GoNiuM puhinatum. The holster-shape Gonium. — 

 When young, this animalcule is merely a simple, flat, 

 quadrangular membrane, with the corners sometimes 

 projecting like a pincushion. The surface in a short 

 time becomes indented, and the square appears like three 

 or four bolsters or pillows attached side to side : other 

 markings are soon observed at right angles to the Ifirst, 

 forming the mass into small squares, as represented in 

 figure 97. These smaller squares, when sufficiently 

 matured, separate, and soon form into clusters, like the 

 parent one. It sometimes happens that while the ani- 

 malcule is merely divided into pillows, before the smaller 

 squares are formed, it increases in length, and a single 

 line is observed across the middle, presenting the ap- 

 pearance of two squares of four pillows each, attached 

 by their ends. They swim about much in the manner of 

 the last species. 



I67. Gonium trichina, The bristled Gonium. — This 

 species has not been hitherto described. It is of a bright 

 green colour, and composed of four pillow-shaped bodies, 

 each corner of the cluster being furnished with a single 

 strong bristle, as shewn, greatly magnified, at figure 96. 

 When arrived at maturity, the cluster separates, some- 

 times in twain, forming two new ones, consisting of two 

 pillows each : when this happens, bristles are soon pro- 

 duced at the two corners which before united the for- 



