13 



found tangled together (see Fig. 13) in great numbers, 

 and twisted roundl weeds, etc., on wliich their eggs are laid. 



The t'resh-water Ch.etopods are practically all 

 Oligoch.kta, chiefly small forms living in the nuid 

 round the roots of aquatic plants, or plants growing near 

 the edge of the water. Samples of nuid scraped up from 

 the bottom of any pond, ditch or stream may contain 

 many of tliese worms. Polych^ta are exceptionally 

 found in fi'csli water, and these are most likely to be 



obtained by dredging in large 

 lakes. In brackish water, on 

 the other hand, Polych^tes 

 are numerous, living in the 

 mud, under stones, etc., as do 

 those of the sea-shore. 



Leeches are often abundant 

 in ponds, ditches and streams, 

 where they swim with an un- 

 dulating movement, or attach 

 themselves to solid objects, and 

 walk like "looper" caterpillars. 



(r) Land forms. 



A number of Planarians (see 

 Fig. 14) crawl about in moist 

 places, or may be found among 

 wet vegetation, such as mosses, 

 or under stones and decaying 

 logs. Some of them suggest 

 slugs, others are more elongated, 

 but they are to be recognised by 

 their extremely soft and slimy 

 bodies, having no tough skin 

 like molluscs or other worms. 

 Land Planarians are chiefly, 

 iDut not exclusively, tropical. 



Nemertines are rare on 

 land, but one or two have been recorded. They are 

 likely to be found in wet places, under stones, &c. 



Nematodes of minute size are abundant in soil and 

 among roots of grasses and other plants. Some are 

 parasitic on plants, and form various kinds of galls and 

 other diseased growths on grasses, &c. Mermis, as already 

 mentioned, is at first parasitic in Insects, but after 

 emergence from them is often found crawling about on the 

 soil or on plants, sometimes in large numbers, especially 

 after rain. It resembles Gordius in its very wiry 

 appearance. 



FKiURE la. 



A tangled mass ol' Gordiits aquatlcus, 

 natural size. [Nematomorpha.] 



