Illinois OligocJueta. 455 



is somewhat elongated and occasionally protrudes backward 

 into the . sperm-sac as far as the posterior part of XII. The 

 diameter of that part of the duct nearest the funnel is very 

 small (.01mm.), and that of its lumen not over .003 mm. 

 The diameters of duct and lumen both gradually increase 

 as the spermiducal gland is approached, and the course of 

 the duct becomes more tortuous. That part of the duct to 

 which the spermiducal gland is attached is expanded into an 

 elongated chamber or "atrium" (PI. XXXIX., Fig. 3), of 

 which the diameter is about .05 mm., that of its lumen being 

 .025 mm. Between the spermiducal gland and the pore the 

 sperm-duct is about .03 mm. in diameter where smallest. 

 The duct terminates in a protrusible penis, which is destitute 

 of a chitinous sheath. The spermiducal pores are in line 

 with the ventral setae of adjacent somites, and also with that 

 row of papillae which is associated with the setae. As before 

 stated, there are no ventral setae on XI. There are two median 

 sperm-sacs, lying dorsad of the alimentary tract ; an anterior 

 one in IX, and a posterior one in XI-XIV. In some cases 

 the latter extends into XV. 



One pair of spermathecae is present in X, and in one of the 

 sectioned specimens there is an additional spermatheca 

 in the right side of IX, which is similar in every way to those 

 of X except that it is slightly smaller. In the specimens 

 examined none of the spermathecae contained any traces of 

 spermatophores. The spermathecal duct is nearly uniform 

 in diameter, and its length is one and a half to two times as 

 great as the diameter of the sac. In each case observed the 

 sac appeared like a hollow sphere with a broad invagination 

 of one side, but whether or not this collapsed appearance is 

 the normal one lias not been determined. There seems to be 

 no difference in the character of the wall in the different parts 

 of the sac, and no glands have been found in connection with 

 the spermathecal duct. The male organs are well developed 

 in all the sectioned -specimens studied, but the ovaries have 

 not contained large ova, nor have there been any traces of 

 ovisacs or oviducts. These specimens were collected in 

 October, and the height of sexual activity is probably attained 

 at some other time of the year. 



