CH. I] EARTHWORMS AND LEECHES 33 



BRITISH OLIGOCILETE WOKMS. 



[The nomenclature, classification, and descriptions (in so far as 

 necessary for British Oligochsetes) here adopted are those given 

 by Dr Wilhelm Michaelsen in Das Tierreich, 10 (Friedlander 

 and Son, 1900).] 



Family ^EOLOSOMATID^. Septa incomplete or absent. Brain not 

 separated from hypodermis. Asexual reproduction frequent. 



genus jEolosoma Ehrbg. Skin usually with oil glands. Prosto- 

 mium ventral, ciliated, not separated by a furrow from next 

 segment. Setae in four groups, two dorsal and two ventral. 

 Testis in 5th, ovary in 6th, unpaired. Spermathecae simple, 

 1 to 3 pairs in segments 3rd to 5th. 



A. quaternarium Ehrbg. Oil glands orange red. Prostomium 

 not broader than following segment. Nephridia absent from 

 region of oesophagus. Total segments 7 to 10 : very small. 

 In slime covering stones in fresh water. 



A. beddardi Mchlsn. Oil glands absent. Prostomium broader 

 than following segment. Length about 2 '5 mm. Total seg- 

 ments 8. 



A. hemprichi Ehrbg. Oil glands orange to carmine. Prostomium 

 broader than following segment. Length 2 to 5 mm. Total 

 segments 4 to 13. In wells, tanks, etc. 



A. headleyi Beddard. Oil glands light green or bluish. Pro- 

 stomium broader than following segment. Length about 

 2 *5 mm. In fresh- water aquaria. 



A. variegatum Yejd. Oil glands partly colourless, partly yellow 

 or greenish-yellow. Prostomium broader than following seg- 

 ments. Nephridia absent from ossophageal region. Has 

 occurred in Ireland. 



A. tenebrarum Vejd. Dirty white. Oil glands faintly yellow. 

 Prostomium broader than following segment. Nephridia 

 present in oesophageal region. Length 5 to 10 mm. In deep 

 wells. 



L. 3 



