536 Illinois State Laboratortj of Natural History. 



plete somites <^ 6 is subdivided. In addition to these there 

 are some incipient differences, but they are too minute to be 

 used in this connection. The larger size and subdivision of 

 the annulus i^* 6 is a very ol)vious and constant character. It 

 is true that many of the other annuli at times show faint 

 cross-furrows, but these lack the constancy, depth, and com- 

 pleteness of the diagnostic one. 



KejyrodKctive Organs. — The testes are larger and fewer than 

 in E. pinietata. In one specimen they average thirty-two to 

 each side of each somite. As in that species, they extend 

 from the posterior part of XVIII to XXI\'. The vasa defer- 

 entia {vd), sperm-sacs (ss), and the greater part of the ducti 

 ejaculatorii (de, PI. XLVIL, Fig. 36) exhibit no important 

 differences ; but the anterior ends of the latter stop short at 

 the anterior limit of somite XII, where they join the apical 

 ends of the prostate cornua. When the copulatory organ is 

 fully retracted the ducti form no loops whatever anterior to 

 these cornua ; but when it is protruded the latter are drawn 

 somewhat caudad, leaving a short sweep of the ductus 

 anterior to it on each side. The prostate cornua (p), though 

 prominent, are shorter than in E. punctata and diverge more 

 widely laterally. A third important difference is found in 

 the presence of a well-developed median atrial chamber {at). 

 This is quite undivided in the median line, where the nerve 

 cord, instead of sinking between two separated lobes, is raised 

 some distance above the body floor. The prostate glands 

 cover the dorsal portion of this chamber as well as the bases 

 of the prostate cornua. 



The protruded male copulatory organ differs in some 

 details from that of E. punctata. It is relatively larger and 

 especially higher. It is supported on a broad pedicle which 

 projects freely through the male pore. Around the entire 

 edge of the disc is a groove which divides it into a proximal 

 and distal circular ridge. The latter bears a delicate ring- 

 like flange which probably corresponds to the muscular 

 border here present in E. punctata. The central cushion is 

 subcircular, and instead of two widely separated openings has 



