176 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.52. 



erablj thickened and 13/14 and 14/15 more strongly thickened. Lon- 

 gitudinal partitions of calciferous gland, 60-64 in number. Sperm 

 sacs in 11 and 12. Spermathecae are lacking. 



H. zeteki is found in the wood and under the bark of decaying logs 

 and sometimes under the logs. It has been collected in considerable 

 numbers in Illinois, Indiana, and Michigan. 



HELODRILUS (BIMASTUS) TENUIS (Eisen). 



Allolobophora tenuis Eisen, 1874fl:44. 



Helodrilus (Bimastus) tenuis Smith, 1914:364. 



Allolobophora constricta Rosa, 1884:38. 



Allolobophora (Bimastus) constricta Michaelsen, 1900:8. 



Helodrilus (Bimastus) constrictus Michaelsen, 1900a:503. 



? Allolobophora norvegica Eisen, 1874:48. 



Length, 4-8 cm. Somites, 90-105. Color of antero-dorsal sur- 

 face, rose-red; elsewhere pale. Prostomium, cpilobic §. Setae, 

 widely paired; aa:ab:hc:cd:dd= 12 -.5 •.10:7 -.35 is an approximation to 

 the relation at a short distance posterior to the cliteUum. ChteUum 

 on 26-31. Tubercula pubertatis, indistinct and often lacking; when 

 present, usually on 29 and 30, occasionally invading 31. Ventral 

 setae of 16, usually borne on broad glandular papiUae. First dorsal 

 pore on 5/6. Spermiducal pores on 15, between h and c on prominent 

 glandular elevations. Oviducal pores on 14, slightly dorsad of 6. 

 Septa but slightly thickened anywhere. Longitudinal partitions 

 of calciferous gland, about 40 in number. Sperm sacs in 11 and 12. 

 Spermathecae, lacking in the typical form; sometimes imperfectly 

 developed. 



Three specimens of the original collection, on which Eisen 's descrip- 

 tion of H. tenuis was based, were given by him to the United States 

 National Museum; and one of these has been partially sectioned as 

 a basis for the study of the internal anatomy and hence of the rela- 

 tionships of the species. 



This specimen is strongly contracted and obviously has lost the 

 posterior end. The length is but 2.2 cm. and the number of somites 

 butSO. On somite 35, aa:a&:6c:c(Z:(Z(^ = 7:3:6:4:15. ThechteUumis 

 on 26-31, but not strongly developed, and the specimen was appar- 

 ently not at the height of sexual activity. Tubercula pubertatis are 

 on 29 and 30 and include setae h. Septa 7/8-9/10, 13/14, and 14/15 

 are very slightly thickened. Longitudinal partitions of the calcif- 

 erous gland are about 40 in number, but can not be exactly enumer- 

 ated in the longitudinal sections of one side. The ''hearts" are in 

 7-11, the last pair being about as large as those of 10. There are 

 paired sperm sacs in 11 and 12, and there are no traces of sperma- 

 thecae. 



It is practically certain that this is the species which has been 

 identified as H. constrictus in this country, and highly probable that 

 it is the same as the H. constrictus of other regions. 



