OXFORD UNIVERSITY SPITSBERGEN EXPEDITION. 1137 



present. Qijsophagiis dilates faii'lj suddenly in segm. vii. Yery 

 numerous parasitic Ciliates in ogsopbagus ; parasites also in 

 oesophageal wall; a cyst outside, in the coelom. Much of the 

 alimentary epithelium is degenerating or has been shed. Doi-sal 

 vessel originates in xiv. ; the blood stains with eosin. Nepliridia 

 of the type found in the genus ; the duct goes backwards at first, 

 then forwards, ending finally a very little way behind the inter- 

 segmental groove, indeed almost in it. 



Clitellum only slightly marked, extending over xii. a,nd xiii. 

 Avith tlie greater part of xi. also. Testes lobed, but not " divided." 

 Sperm-sac present, extending into xiii. Funnel as yet merely a 

 plate of cells on the septum ; vas deferens onlj^ as a solid cord 

 of cells, cylindrical and somewhat wavy, from funnel to male 

 aperture. Penial bulb as a number of loosely arranged cells 

 around the terminal portion of the vas deferens. Ovisac ex- 

 tending back to xvii. Spermathecal ampulla not distinguishable; 

 duct narrow, no gland-cells round its ending, cylindrical, of some 

 length, coming to the surface in the tract of the lateral line cells. 



The distinction of species of Mesenchytrceus depends largely on 

 the characters of the vas deferens and spermathecal ampulla — 

 just those portions of the sexual a^pparatus which are most 

 undeveloped in the present specimens. 



References to Literature. 



(1) Beddard, F. E.— a Textbook of Zoogeography. Cam- 



bridge, 1895. 



(2) Bretscher, K. — tjber ein neues Enchytriiidengenus. Zool. 



Anzeiger, xxix. 1906. 



(3) Cejka, B. — Die Oligochaeten der russischen in den Jahren 



1900-1903 unternommenen Xordpolar Expedition. I. 

 Uber eine neue Gattung der Enchytraeiden {Ilepato- 

 gaster). Mem. Acad. Sci. St. Petersb. (8) xxix. no. 2, 

 1910. 



(4) Cejka, B.— 76. II. Uber neue Bryodrilus und Henlea- 



Arten. lb. (8) xxix. no. 6, 1912. 



(5) Delphy, J. — Etudes sur Torganisation et le developpement 



des Lombriciens limicoles thalassophiles. Paris, 1921. 



(6) EiSEN, G. — Enchytraeids, in Harriman Alaska Expedition, 



vol. xii. New York, 1904. 



(7) Friend, H. — A Key to British Henleas. Zoologist, (4) xvii. 



1913. 



(8) Friend, H. — British Enchytrseids. YI. New Species and 



Revised List. Journ. R. Micr. Soc. 1914. 



(9) Friend, H. — Studies in Enchytrseid Worms. Henlea 



fragilis Friend. Ann. Applied Biol. ii. 1915. 



(10) Michaelsen, W. — Synopsis der Enchytraeiden. Abh. Yer. 



Hamburg, xi. Heft i., 1889. 



(11) Michaelsen, Yi. — Oligochasta, in Das Tierreich, vol. x. 



Berlin, 1900. 



