Reactions of jEolosotna to Chemical Stimuli 



45 



outlining a general method of procedure; to Profs. E. G. Conkin 

 and j. Percy Moore for many valuable hints and corrections. 



NATURAL HISTORY 



Only very brief references to the natural history of iEolosoma 

 may be found in the literature. Some of these w^ill be noted in 

 passing. No careful investigation into its behavior has been 

 made. 



General Morphology 



yEolosoma is the only genus thus far described of the Oligochae- 

 tan family, iEolosomidae (Aphanoneura, Vedjovsky). It abounds 

 in fresh water ponds and streams throughout the equatorial and 

 neo-arctic regions A schematic drawing of the anima lappears 

 in Fig. I. The different species vary in length from about I mm. 



Fig. I. Ventral View of Jiolosoma. 



A Sensory hairs E Pharynx I Intestine 



B Prostomium F Muscle fibers K Caudal segment 



C Buccal cirri G Oesophagus L Papillae 



D Peristomium 



H Stomach 



(A. quaternarium) to about lo mm. (A. tenebrarum). The seg- 

 ments, expressed chiefly in epidermal structures,- are from 5 to 15 

 or more in number. The brain, or cerebral ganglia, and the ven- 

 tral nerve cord, are noteworthy in that they are buried in the 

 epidermis (Vedjovsky '84). Each segment, with the exception 

 of the head segment, and the budding zones, bears four bundles 

 of setae. The head segment bears a prominent flexible upper lip, 

 or prostomium, which is ciliated on the under side. The prosto- 

 mium is thin dorsoventrally, and is concave on the under side, 

 making it somewhat spoonshaped. Circling about the tip of the 

 prostomium project little spines or hairs, which are connected 



