158. 



7. Lip region conoid, projecting ...... oo. . atecki Steiner, I91U 



Lip region low, rounded 



. ziinmermanni (Bally and Reydon, 1931) Th. and Swang., I936 





8. Inner portion of lip region set off ...... . minimus de Man, 18? 6 



Inner portion of lip region not set off 9 



9. Tail dorsally convex and subdigitate 



..... brevicaudatus (Tarjan, 1953) Tarjan, 19^6 



Tail hemispherical or bluntly conoid 10 



10. Tail hemispherical nanus Thorne, 1939 



Tail bluntly conoid proximus Thorne, 1939 



11. Tails ventrally arcuate .... nikkoensis Kabruaki and Imamura, 1933 

 Tails blunt, roiuided 12 



12. Spear massive ... kirifuri Kabruaki and Imamura, 1933 



Spear minute steineri Schneider, 1935 



Geniis T<'nchodelus Thorne, 1939 

 (Key to the species modified from Thorne, 1939) 



1. Tails hemispherical or rounded- conoid 2 



Tails eloni^ate, elongate-conoid, straic^ht or ventrally arcuate. . . 10 



2. Spear extensions oroadly flanged 3 



Spear extensions not broadly flan-ed, lineate 6 



3. Lips somewhat angular hopedorus (Thome, 1929) Thorne, 1939 



Lips low, rounded I4 



U. Length about 1.0 mm vesuvianus Cobb, 1893 



Length 1.5 mm or over 5 



5. Length near 1.5 mm. . . . macrodorvs (de Man, I88O) Th. & Swang., 1936 

 Length near 2.5 mm. . • • groenlandicus (Ditlevsen, 192?) Thome, 1939 



6. Tail elongate conoid, 1.5 - 2.5 anal body diameters 



..... .... conicaudatus (Ditlevsen, 1927)a 



Tail bluntly conoid, equal to anal body diameter. . . Thorne, 1939- .7 



7. Lios angular 8 



Lips rounded. 16 



8. Tail with about 50 saccate bodies on each side, nearly uniformly 



bluntly conoid teres, Thorne, 1939 



Tail with about 12 saccate bodies on each side, dorsally convex 

 bluntly conoid vestibulifer Altherr, 1952 



9. Spear length equal to lip region width laevis Thorne, 1939 



Spear length twice lip region width 



analatus (Ditlevsen, 192?) Thorne, 1939 



