3444 



THE WORM-LIKE ANIMALS 



in the solid tissues of some of the species of Convoluta are large numbers of cells 

 containing chlorophyll, or the green coloring matter of plants. These cells are 

 probably minute plants (Algce), which have taken up their abode parasitically in 



the worm. In addition to the ordinary means 

 of reproduction by sexual organs, some of the 

 rhabdocoelans multiply by division. 



The accompanying illustration shows one 

 of these worms (Stenostomum monocelis) in process 

 of giving rise to a second individual. In the 

 upper half of the figure (0) is the mouth, and O) 

 the auditory organ of the parent; the coiled 

 tube (v) being part of its excretory apparatus, 

 and O) some eggs. In the lower half (o) is the 

 mouth, and (s) the auditory organ of the newly- 

 forming individual. The division may begin suc- 

 cessively at several places on the body before the 

 last and oldest bud is attached, so that it results 

 in the formation of a chain of segments lying 

 one behind the other. 



SUBORDER Dendrocoela 



The members of this division differ from 

 the preceding in having the intestinal canal 

 tree-like, or divided into a number of branches. 

 The mouth, which is situated on the inner 

 surface, leads into a muscular and flexible 

 pharynx, capable of protrusion like a proboscis. 

 The body is broad and flattened, usually broader 

 in front than behind, and generally bears a pair 

 of eyes upon what may be termed the head. 

 In the genus Palycelis the species of which 

 occur in meadows and stagnant water there 

 are a large number of eyes, the broad front end 

 of the body being bordered with from thirty to 

 fifty of these organs. On the other hand, 

 Geoplana siibterranea, which lives in sandy and 

 clayey soil, in company with earthworms, upon 

 which it feeds, is entirely devoid of organs of 

 sight. Many members of the group are in- 

 habitants of the land and fresh water, and are 

 collectively termed Planarians. These are often 

 objects of considerable beauty, being both 

 graceful in movement and decked with various 

 colors. The two-striped Geodesmus bilincatus, 



SINGLE-EYED TURBEHARIAN, Steno- 

 stomum (much enlarged). 



