ENCHYTR^EID^E 



47 



For want of specimens of M. grandis this relationship cannot now 

 be cleared up. It may be possible that M. grandis is identical with 

 M. harrimani, the spermathecae having become accidentally reduced. 



MESENCHYTR^EUS FUSCUS sp. nov. 



pi. viii, figs. 3-5; text-figs. 21-23. 



Definition. Length 15 mm., width i mm. Somites 58. Setae 

 sigmoid : laterals, 3, 3, 3, 3, 4 ; postclitellars 3, 3, 4, 4, 4 ; ventrals, 6, 

 6, 7, 7, 7, 6 ; postclitellars, 6, 6, 6, 5 (5, 3, 2). Head-pore large, near 

 the apex. Clitellum, dorsally XI-XIII, ventrally | XI-XIII. Copula- 

 tory papilla of medium size. Intestine in II and III much narrower than 

 in the following somites. Septal glands in somites III- VI. Brain 

 posteriorly truncate, anteriorly deeply incised. Dorsal vessel rises in 

 somite XX 

 and at once 

 is very thick. 

 Spermatheca 

 with two saus- 

 age-shaped di- 

 verticles nearer 

 the pore than 

 the intestine. 

 The diverticles 

 are about one- 

 third as long 

 as the whole 

 spermatheca. 

 Sperm-ducts 

 about twelve 

 times as long 

 as the funnel, 

 extending back 

 some nine so- 



Mesenchytraus fuscus. 



mites, or to XXI. Funnels very large, helix-shaped. An atrial 

 chamber into which open independently of each other six to eight glands. 

 Penial glands opening at the base of the sperm-ducts. Sperm -sacs very 

 large, one pair extending as far back as somite XXVII or further. One 

 ovisac. Nephridia with two almost circular lobes. Lymphocytes 

 few, flat and circular. 



Locality. In moss in Pit River (below the falls), California. 

 Also from several other localities in northern California. Collected 

 by Dr. Richard C. McGregor. 



