pO EISEN 



riorly slightly emarglnate. Color bright ochraceous yellow (alcoholic 

 specimens). Ventral glands very large (but not as large as in L, 

 franciscanus var. borealis)^ in XIII and XIV. Lymphocytes large, 

 oval, pointed, numerous. In other respects sim- 

 ilar to the species. 



Distribution. — Unalaska, Prof. Trevor Kin- 

 caid (September). 



Characteristics . — The squareness of the brain 



and the fact that all the seta are of the same 



size in each fascicle distinguishes this variety 



Fig. 59. Lumbricillus from L.f. borealis. From the species it differs 



franctscatius un- principally in size and in the form of the brain. 



As regards the number of setae, this variety stands 



betw^een the species and Z. f. borealis. 



Genus Marionina Michaelsen. 



Dejinition. — Setae sigmoid, as in Lui}tbricillus. Head-pore small, 

 betw^een prostomium and somite I. No dorsal pores. Blood red or 

 yellovs^. Dorsal vessel rises posterior to clitellum. No cardiac gland. 

 No peptoneploridia. Sperm-ducts comparatively long and narrow. 

 Penial bulb without interior muscular strands. Testes undivided, each 

 covered by a small sperm-sac. Ventral glands present or absent. 

 Nephridia with entire postseptal and with comparatively large head- 

 like anteseptal. 



To the original definition of this genus I have added the char- 

 acters concerning the testes and their sperm-caps and the structure of 

 the penial bulb. The principal difference between Marionina and 

 Lumbricillus concerns the testes, as is now well known. But I think 

 that another difference may be derived from the nephridia, which in 

 Marionina seem to be characterized by a large head-like anteseptal, 

 while in Lumbricillus the anteseptal consists of merely the nephro- 

 stome. 



DETAILED DESCRIPTION. 



Penial bulb. — The penial bulb resembles that of Lumbricillus In 

 general structure. There are two sets of glandular cells opening in 

 the bulb. One set opens into the lower part of the sperm-duct, while 

 the other opens onto the base around the pore. 



Nephridia. — These organs have not been described in all species 

 and general conclusions cannot therefore be made for the present. 

 There seem, however, to be two types, one with a short anteseptal 

 consisting of a mere nephrostome, while the other type possesses a 



