538 Illinois State Laboratory of Natural History. 



mm. 

 Total length, . . . " . . . 42. 



Length to male pore, . . . . . .10. 



Width at male pore, 3.4 



Greatest width (middle), 4.2 



Width at anus, '• 3.5 



Depth at male pore, .... about 1 . 5 



Depth at middle, about 2 . 



Depth at anus, . . . • • .1.2 



Diameter of posterior sucker, . . . . 2.5 



The width is greatest at about the middle of the body but 

 varies little in the entire postclitellal region. The margins of 

 the body are rounded except just about the anal region, 

 where lateral flanges begin at about XXIII and become 

 more and more prominent until they terminate in a pair 

 of thin expansions which embrace the base of the sucker. A 

 curious feature which appears in a great many specimens 

 is a short contracted region just behind the clitellum, where 

 the body becomes perfectly terete and bellies ventralward. 

 From the genital region forward the body tapers quite rapidly 

 to a point just posterior to the mouth and then rapidly con- 

 tracts into the narrow lip. As in nephelids generally, the 

 entire body is covered with small sensory papillae arranged 

 in zones on every annulus. 



The mouth is small, even in specimens which have been 

 killed in a much relaxed condition. In most specimens the 

 upper lip is extended, slender, and prominent, and is often 

 most sharply distinguished from the succeeding annuli by a 

 deep furrow which passes behind the postoral ring. Dorsally 

 it is smooth, divided into distinct but very narrow rings, and 

 provided around the margins very richly and above sparingly 

 with labial sense organs. 



There are three pairs of eyes, of which the first are the 

 largest and are situated on somite III, instead of on II as in 

 most nephelids. Sometimes one or each of these is repre- 

 sented by two. The second and third pairs are on IV, the 

 dorsalmost slightly in advance. 



