NO. 2174. EARTHWORMS OF THE FAMILY LUMBRICIDAE— SMITH. 161 



family and is tentatively subdivided by Michaelsen into six sub- 

 families, not veiy sharply defined, of which five are represented in 

 North America. 



Genus HELODRILUS Hoffmeister, 1845. 



The chief character, by which species of this genus are distinguished, 

 is the absence of any special sperm vesicles enclosing the spermaries 

 and spermiducal funnels. 



Subgenus Eiseniella Michaelsen, 1900. 



For synonomy see Michaelsen (1900a: 471). 



Michaelsen (1910) has reduced this group from generic to sub- 

 generic rank and considered its relationships to the subgenus Eisenia 

 (Malm) to be so close as to hardly warrant their separation. The 

 only character used as a basis for such separation is the somewhat 

 shorter gizzard which is chiefly confined to the 17th somite in 

 Eiseniella and ordinarily involves, in addition, more of the 18th 

 somite in others. A much more significant character is probably 

 to be found in the position of the oviducal pores. My study of 

 American material of Helodrilus tetraedrus f . typica, H. t. f. hercynia, 

 and Eisen's Tetragonurus pupa has shown in every specimen exam- 

 ined, the oviducal pores opening shghtly mesad of a instead of slightly 

 dorsad of h; where, as far as known, they open in aU other Lum- 

 bricidae. If similar relations are found in European material, as is 

 probable, the retention of the subgenus will be on a much better basis. 



Eiseniella differs from the other subgenera, except Eisenia, in 

 having the pores of the paired spermathecee between the seta line 

 d and the mid-dorsal line. 



HELODRILUS (EISENIELLA) TETRAEDRUS (Savigny) forma TYPICA. 



Entcrion tetraedrum Savigny, 1826: 184. 



Allurus tetraedrus Eisen, 1874: 54. 



Eiseniella tetraedra (typica) Michaelsen, 1900o.; 472. 



Helodrilus {Eiseniella) tetraedrus forma typica Michaelsen, 1910: 11. 



For more complete synonomy of this and other species, see 

 Michaelsen, 1900a. 



Length, 3-6 cm. Somites, 70-90. Color, quite variable, but 

 usually some shade of brown. Prostomium usually epilobic. Setae 

 paired ; slightly posterior to clitellum, aa: ah: Ic: cd: dd = S: 1:3: 1:6; 

 near posterior end, aa: ah: he: cd: dd = 5: 2:5:2: 6-8. CliteUum on 

 22 or 2.3-26 or 27. Tubercula pubertatis on 23-25 or 26. Fu-st 

 dorsal pore on 4/5. Spermiducal pores on 13. Oviducal pores 

 on 14, slightly mesad of a. Spermathecal pores on 9/10 and 10/11 

 between d and mid-dorsal line. Septa, 7/8-11/12 slightly thickened. 

 Longitudinal partitions of the calciferous gland, narrow and the 

 65008°— Proc.N.M.vol.52— 17 11 



