DESCRIPTIONS OF GENERA AND SPECIES 



319 



long with two oval diverticula ; sperm-duct eight times the length of the comparativeli/ 

 small funnel. Hah. — Germany. 



This species has been described by Michaelsen in two papers quoted above. 

 The species has two short sperm-sacs confined to the twelfth segment ; the egg-sac 

 is single, but in one instance it was found to be divided into two at its extremity ; 

 the egg-sac extends as far back as the nineteenth segment. The egg-sac in 

 this species shows no constrictions at the septa, as is so often the case. The 

 •perivisceral corpuscles are ellipsoidal. The septal glands are in iv and v ; from 

 these a band passes back on each side as far as vii, from which arise irregular lumps 

 of gland-cells. The dorsal vessel springs in xviii ; it has swellings in this and the 

 three segments lying in front. The clitellum occupies segments xi-xiii. 



(7) Mesenchytraeus flavidus, Michaelsen. 



Mesenchytraeus flavidus, Michaelsen, Arch. Miki-. Anat. 1887, p. 37a. 



Definition. Length, i a mm. ; setae, up to Jive per hmdle. Sperm-duct at most five times us 

 long as funnel ; spermathecae without diverticula, dilated at distal extremity. Hob. — 



The dorsal vessel arises in the thirteenth segment. The sperm-duct is only about 

 five times as long as the funnel ; it has small prostates. The clitellum occupies 

 segments xi-xiii. 



(8) Mesenchytraeus setosus, Michaelsen. 

 Mesenchytraeus setosus, Michaelsen, Ai-ch. Mikr. Anat. 1 888, p. 494. 



Definition. Length, i^mm.; 1-12 setae per bundle, those of the lateral bundles of segments, 

 V — VIII, much larger^ than others, and fewer in a bundle. Spermatheca with a single 

 shm-t diverticulum, close to its oesophageal opening. Hab. — Germany. 

 This species shares with the doubtful M. armatus the peculiarity in the setae 



' The exact numbers in the bundles of anterior segments are, according to Michaelsen. as follows 

 (large setae indicated in thick type) : — 



