NO. 2174. EARTHWORMS OF THE FAMILY LUMBRWIDAE— SMITH. 159 



cells produced in those somites. Each sperm sac hes in a somite 

 adjacent to the one into which it opens. These organs are often 

 called seminal vesicles in the textbooks. 



In the following key marginal numbers in parentheses refer to 

 other paragraphs in the key which contain alternative statements 

 which are to be compared with the one concerned and a decision made 

 between them. 



TECHNIC. 



An adequate study of earthworms for systematic purposes de- 

 mands serial sections of sexually mature specimens, although much 

 important information can be gained from careful dissections. 



When there is scarcity of material and in dealing with types, the 

 writer, beginning at the anterior end and using a safety razor blade, 

 splits the specimen in the sagittal plane as far as desired and at 

 least through the 16th somite. A piece on one side of this cut is re- 

 moved and made into serial sagittal sections. If there is dirt in the 

 alimentary tract in the piece to be cut, it must be removed before im- 

 bedding. One is less likely to lose sections at the end of the series 

 if he begins sectioning on the side opposite the cut surface. 



KEY TO SPECIES OF LUMBRICmAE REPOKTED IN NORTH AMERICA. 



1 (41) Prostomium incompletely divides the peristomium, epilobic 2. 



2 (40) Spermaries and spermiducal funnels not inclosed in sperm vesicles. (Anterior 



margin of clitellum is anterior to 30 in species included in this key.) Ilelodrilus .3. 



3 (17) Spermathecal pores, dorsal to seta line d, near mid-dorsum 4. 



4 (9) Posterior margin of clitellum not extending as far as 29; antero-dorsal surface of 



body pigmented with some shade of brown . Amphibious. Subgenus Eiseniella .5. 



5 (6) (7) (8) Spermiducal pores on 13; clitellum on 22 or 23-26 or 27. 



//. (E.) tetraedrus typica. 



6 (5) (7) (8) Spermiducal pores on 15; clitellum on 22 or 23-27. 



n. (E.) tetraedrus hercynia. 



7 (5) (6) (8) Spermiducal pores on 13; clitellum on 20 or 21-24 or 25. 



H. (E.) tetraedrus neapolitana. 



8 (5) (6) (7) Spermiducal pores on 15; clitellum on 20 or 21-24 or 25. 



H. (E.) tetraedrus ninnii. 

 9(4) Clitellum extending posteriorly at least to 29 Subgenus Eisenia. 10. 



10 (11) Setae widely paired; ab:bc:cd— 5:9:5 H. (E.) venetus hortensis. 



11 (10) Setae closely paired 12. 



12 (13) Three pairs of spermathecal pores, 8/9, 9/10, and 10/11; clitellum, 24-30. 



H. (E.) lonnbergi. 



13 (12) Two pairs of spermathecal pores 14. 



14 (15) (16) Clitellum, 24-31; tubercula pubertatis, 27-29. ...H. (E.) carolinensis. 



15 (14) (16) Clitellum, 24, 25 or 26-32; transversely banded with brown and buff. 



H. {E.)foctidus. 



16 (14) (15) Clitellum, 24, 25 or 26-31, 32 or 33; tubercula pubertatis, 29-31; without 

 ■ pigment H. (E.) roseus, 



17 (3) Spermathecal pores, when present, in or ventral to seta line d 18. 



18(22) (25) Four pairs of sperm sacs in 9-12; spermathecae present; setae closely 



paired Subgenus AUolobophora .19, 



