314 OLIGOCHAETA 



Genus DISTICHOPUS, VERRILL. 



DEFINITION. 'Form and colour as in EncJiytraeus, with a well-produced girdle. 

 Setapods in a single row on each side ventrally, in divergent fascicles of four in 

 advance of the girdle and of three behind it.' 



There is but one species in this genus which is regarded by MICHAELSEN as a ' species inquirenda.' 

 This species, called D. sylcestris, is 20-30 ram. in length and composed of sixty-eight segments. 



Genus CHIRODBILTJS, VERRILL. 



DEFINITION. 'Allied to Saenuris, but with six fan-shaped fascicles of setae upon each 

 segment, two of which are ventral, two lateral, and two sub-dorsal ; setae in the 

 ventral and lateral fascicles four to nine, simple, acute, slender, curved like 

 an italic f ; those of the dorsal fascicles stouter and less curved, three to six in 

 each fascicle. Intestine wide, somewhat moniliform. Anus terminal, large.' 



I follow MICHAELSEN in assigning this genus to the family Enchytraeidae. Both VEJDOVSKY 

 and VAILLANT place it among the Tubificidae. As MICHAELSEN has pointed out (5), the shape 

 of the setae and the colourless blood together are inconsistent with any other view upon the 

 systematic position of the two species which comprise the genus. The clitellum, too, is developed 

 (in C. lan-iformis) upon the eleventh seta-bearing segment and upon a small part of the following 

 segment, which is precisely what occurs in other Enchytraeids. The two species of the genus 

 described by VEKHILL are C. lairiformis and C. abyssointm ; they were both dredged in Lake Superior. 

 In C. abyssomm the dorsal-setae are described as being shorter than those of both lateral and^ventral 

 bundles. Both species are small, 6 or 8 mm. in length, with thirty-eight or forty-two segments -- 

 another argument, not noticed by MICHAELSEN for their being referred to the Enchytraeidae. 



Genus MESENCHYTRAEUS, EISEN. 

 Syn. Analycus, LEVINSEN. 



Enchytraeus, VEJDOVSKY (in part.). 

 Neoenchytraeus, EISEN (in part.). 

 Pachydrilus, VAILLANT (in part.). 



DEFINITION. Setae ./-shaped, usually more numerous in the ventral than in dorsal 

 bundles of anterior segments. Head -pore usually near to anterior end of 

 prostomium, no dorsal pores. Dorsal vessel arises behind clitellum, contains 

 a cardiac gland, blood colourless. No salivary glands. Brain truncated or 

 concave posteriorly, generally broader than long. Nephridia with short ante- 

 septal and large irregularly lobate post-septal portion. Egg-sacs and sperm-sacs 

 present ; sperm-ducts short, at most eight times as long as funnel. 



