292 Illinois State Laboratory of Natur^al History. 



■distance from the prostate glaud to the tuiii. From 

 this point the diameter gradually diminishes, and be- 

 fore reaching- the prostate, becomes smaller than in any 

 other part of the duct. The diameter of the widest part 

 of the duct is one fifth that of the entire worm in that 

 region, and three times the diameter of its own lumen. 



In specimens that have passed the period of sexual 

 activity the sperm duct becomes reduced in size, more 

 -convoluted, and extends backward a shorter distance. 



EnchytrcEiLS littoralis is evidently very closeh' related to 

 E. t'ejdovshyi Eisen (3, p. 25) and E. humicultor Vejdov- 

 sky (17, p. 57). The chief difference would seem to be 

 in the sjx^rm duct, which in E. littoralis extends back as 

 far as XVIII, but which at the height of sexual activity 

 is entirely free from the numerous flexures described by 

 Eisen (3, Fig. 19h), Michaelsen (6, p. 39; and 7, p. 37), 

 and Ude (13, p. 86) as existing in E. vejdovshyi and E. 

 Jmmicultor. Specimens of E. littoralis are frequently found 

 in which the sperm duct passes from one side of the 

 body to the other once or sometimes twice, but it is 

 without sharp turns except at the point farthest back, 

 where its course is reversed. The somewhat abrupt in- 

 crease in the diameter, already described, is also very 

 characteristic. The brain is similar in form to that of 

 E. vejdovskyl as figured by Eisen (3, Fig. 19f), though less 

 concave in front and less convex behind. In view of 

 the above facts it seems reasonable to question the ad- 

 visability of regarding the differences between the Euro- 

 pean and American forms as more than varietal. Ver- 

 rill's name has priority, of course, in the event of its 

 being necessary to unite the species from the two con- 

 tinents under one name. 



Thinodrilus inconstans^ n. g. et n. sp. 



At various times since April 1894 specimens of a spe- 

 cies belonging to the Lumbriculidae have been collected 

 from the east shore of Quiver Lake, at Havana. They 



