200 F. W. GAMBLE, B.SC. 



Distribution. — West coast of Greenland (Levinsen). 



Levinsen's description (according to v. Graff) left this form indeter- 

 minate. The two pyriform bodies that he called " Samenblasen," and 

 which v. Graff suggested might be local swellings of the vasa 

 deferentia, I take to be the true testes. They have all the structure 

 of such an organ, but occupy a more posterior position than usual. 

 The ova did not appear to Levinsen to be distinguishable into two 

 fairly distinct ovaries as in my specimens. 



Subfamily ByrsophlebiNjE. 



Mesostomidce with two genital apertures, the male, in front of the female. 

 Germarium single. Vitellaria distinct. Accessory organs absent or 

 present. Testes small, rounded. 



Genus 8. — Byrsophlebs, Jensen (49.) 

 (With the diagnosis of the subfamily.) 



15. Byrsophlebs Graffi, Jensen. 



Length "45 mm. Body cylindrical, tapering gradually posteriorly. 

 Colourless, the gut brownish-yellow. Pharynx central, male genital 

 aperture immediately behind it, female aperture close to the hinder end. 

 Penis composed of a proximal cylindrical portion, strengthened by spiral 

 and longitudinal muscles, and a distal chitinous funnel-shaped duct. 

 The terminal aperture of this duct is provided with a short triangular 

 projection on one side. Opening through the female genital aperture 

 is a receptaculum seminis placed at the base of the ovary, and a 

 muscular bursa copulatrix at its side. Yolk-glands unbranched, lateral. 

 (For further account with figures see Jensen (49), pi. ii, figs. 8 — 12.) 



Habitat. — Among algse, Drake's Island, Plymouth Sound (F. W. G.) ; 

 among Ulva and Fucus, Millport (v. Graff.) 



Distribution. — Bergen and Sund, West Norway (Jensen). 



16. Byrsophlebs Intermedia, v. Graff. 



Besembles the former species in most characters, differing in the 

 arrangement of the genital organs. The penis is elongate, cylindrical, 

 the spiral muscular fibres surrounding the united vasa deferentia. 



