XIX.— D ESCRIPTIONS OF TWO FRESH- 

 WATER OI.IGOCH.ETE WORMS FROM 

 THE PUNJAB. 



By J. Stephenson, Major, I. M.S., Professor of Biology, Govern- 

 ment College, Lahore. 



(l) ^OLOSOMA, sp. 



The worm of which the following is a description is very com- 

 mon in and near Lahore ; it inhabits standing water, and may 

 often be found in large numbers in the foul-smelling sediment at 

 the bottom, and also in and amongst algse of various kinds. It 

 lives well in small vessels in the laboratory ; specimens were exam- 

 ined at various times during April 1907. 



Examined with a lens when moving freely at the bottom of 

 the vessel, they appear to glide smoothly forward in an extended 

 condition, without the numerous twists, expansions, and con- 

 tractions of parts of the body that are seen in the case of other 

 small Oligochgeta. On a slide and under a cover-glass they are 

 seen to be extremely contractile, rapidly altering their shape, 

 now short and contracted, now long and extended. They remind 

 the observer somewhat of small Turbellarians. 



The individuals vary very greatly in length, according to the 

 degree of extension of the body, and also according to the parti- 

 cular phase of asexual reproduction in which they happen to be. 

 A single individual showing no sign of axiproaching division may 

 measure about 3 mm. ; usually, however, specimens are longer, 

 show one, two or more constrictions, and may reach 8 mm. There 

 is a well-marked prostomium, followed by a narrower pharjmgeal 

 and oesophageal region ; the region of the stomach is thicker again, 

 and behind this the body is uniformly cylindrical to the posterior 

 end. The whole body shows a large number of spherical, ovoid, 

 or irregularly shaped green bodies scattered in the surface epithe- 

 lium ; their colour varies slightly ; they may be a pure bright 

 green, or green with a shade of brown, or a light yellowish-green ; 

 the latter shades were noticed more frequently, and the pure green 

 less frequently, after the animals had lived for some time in the 

 laboratory. I do not think that these bodies had themselves 

 ever any tinge of blue ; there appeared to be at times a bluish 

 tinge in the other parts of the skin, due to smaller, less defined, 

 somewhat refractile particles of a. very faint blue colour, so faint 

 as to be almost colourless. 



