52 EISEN 



Locality. Popof Island, Alaska, Prof. Trevor Kincaid. 



Characteristics. Only a few specimens were collected, and of 

 these only one was partially adult. The specimen sectioned did not 

 possess any part of the efferent apparatus and no spermathecae. The 

 adult specimen was dissected. The form of the spermathecae and the 



FIG. 26. Mesenchytrceits nanus. 



sperm-funnels opening into the pores without ducts, are so very 

 characteristic that the species cannot very well be confounded with 

 any other species known. The nearest related species is M. primcevus 

 Eisen, which however possesses a slightly different spermatheca, the 

 difference being in the diverticles and in the length of the organ. The 

 duct leading to the pore in the nephridium is much longer in M. nanus 

 than in M. primcevus. 



MESENCHYTRyEUS FONTINALIS sp. nov. 

 pi. i, fig. 15; pi. xi, fig. 3; text-fig. 27. 



Definition. Length 8 mm., width .75 mm. Somites 60. Seta? 

 sigmoid; laterals anterior to clitellum 3, posterior to clitellum 4, 5,6; 

 ventrals anterior to clitellum 6, posterior to clitellum 7, 6. Head- 

 pore large, situated a little posterior to the apex. Clitellum dorsally 

 f XI-XIII, ventrally \ XI-XIII. Sexual papilla? not prominent. 

 Brain posteriorly truncate or very slightly concave. Septal glands large 



