214 MR. F. E. BEDDARD ON A [Mar, '20, 



placed in a drop of water upon a slide moved about with a rapid 

 steady motion, resembling, as Vejdovsky has pointed out, that of a 

 Planarian. Occasionally the movements were more sudden, the 

 worm rapidly twisting itself to one side or to the other. Examined 

 under a lens of moderately high magnifyiug-povver, it was evident 

 that the movements of the animal were caused by the contractions 

 of the muscular layer of tlie parietes. 



The muscular pharynx is used by the animal as a sucker ; it 

 attaches itself so firmly by this, that a comparatively violent disturb- 

 ance of the water is requisite to detach it. When placed upon a 

 slide in a drop of water and covered by a cover-glass, the worms 

 nearly always attached themselves to the latter; I found it, indeed, 

 almost difficult to study the living worm from the dorsal surface. 

 This habit is probably due to the fact that the worm crawls about 

 on the under surface of the flattened branches of the duckweed. 

 As Vejdovsky has pointed out, the oral segment and the procephalic 

 lobe are the most contractile portions of the animal's body, though 

 it can shorten itself and increase its length within rather wide limits. 

 The individuals were in a state of active division, but I did not 

 discover the sexual organs. Such are the most striking facts wiih 

 regard to the habits of the present species of ^■Uolosoma that have 

 come under my observation. 



Our knowledge of the structure of this genus is summed up in 

 Vejdovsky's recent work upon the Oligocliseta', where there is also 

 to be found a critical account of the described species. Since the 

 publication of that work, Vejdovsky has added a new species^, 

 JEolosoma varieyatum, to the three which liave been sufficiently 

 characterized to admit of an adequate definition (^^. quaternarium, 

 j^. ehrenbergi, and ^. tenebrarum) ; the species which I have in- 

 vestigated comes nearest to /E. vuriegatum, but is, I believe, not 

 identical with that species. 



The worm agrees with jE. variegatuni in the green colour of the 

 oil-globules. Zacharias ^ has lately investigated an ^olosoma, 

 which may be identical with JE. variegatutn or with my own species, 

 supposing that they are distinct, and has suggested that these green 

 bodies may he Algcs; they were observed in course of divisimi. I 

 can, however, confirm Vejdovsky's statement that these bodies are 

 coloured black by osmic acid, which is strong evidence of their being 

 of a fatty nature ; furthermore, a carefid observation of the living 

 worm under a high power shows that these green droplets change 

 their form, as the animal moves about, quite after the fashion of an 

 oil-globule ; in the third place, staining with iodine showed no trace 

 whatever of the starch reaction. The green oil-globules were of 

 different sizes, and showed almost every tint of green from a pale 

 yellowish to a dark blue-green ; there ap])eared, however, to be no 

 special relation between the size and the colour. They were far 

 more abundant than Vejdovsky's figures show them to be in 



' System unci Morpliologic der Oligocbaeteu : Prag, 1884. 

 - Sil/.ungsb. bulmi. (iest'llsfli. 1'. \Vit.&fns_-h. 188;'). 

 •* Zcilsclir. i. wiss. Zuul. 1885. 



