ENCHYTR^EID^E 23 



Clitellum. In fully adult specimens the clitellum is white and 

 stands out prominently. This is also the case with the sexual papillae, 

 which project about one fourth the diameter of the body. 



Brain (figs. 26 and 2c) . This organ varies considerably, but in 

 the majority of specimens dissected the form was about square, more 

 or less deeply emarginated posteriorly and very deeply emarginated 



FIG. 3. Mesenchytrceus asiaticus. 



anteriorly. This species is thus one of the very few in this genus 

 possessing a brain posteriorly emarginated. One of the specimens 

 possessed a much more elongated brain than the others, but the emar- 

 gination was even more deep. 



Spermathecce (figs. 30 and 3*:). These organs do not connect 

 with the intestine. They extend into somite VI and are thus slightly 

 enlarged. Diverticle varies in size. In the majority of specimens the 

 size is as figured, but in one specimen the diverticle constituted a mere 

 warty swelling. The width of the ampulla varies considerably, the two 

 extremes found in the dissected specimens having been figured. 



Spermiducal apparatus (pi. xi, fig. 4). Funnels rather long 

 and slightly curved. Sperm-ducts probably six to seven times (or 

 more) as long as funnels. They are twined and extend back 

 several somites. In this respect they differ from those of M. jlavus, 

 which species has short sperm-ducts. The number of atrial glands 

 seems to be always five. Penial bulb is broad, and contains a number 

 of penial glands situated close together. At the base of the sperm- 

 ducts and in the ducts are a number of narrow unicellular glands open- 

 ing inside the sheath. 



