NO. 2174. EARTHWORMS OF THE FAMILY LUMBRICIDAE— SMITH. 177 



The great majority of H. tenuis collections examined by the writer 

 have contained only normal specimens; but four collections made in 

 different localities have each contained in close association speci- 

 mens without spermathecae and others with imperfectly developed 

 spermathecae. The largest of these collections includes 30 or more 

 specimens taken near Bm't Lake, Cheboygan County, Michigan, in 

 1911, from an old manure heap composed of horse manm-e and saw- 

 dust that had been used for bedding. Sections were made from 10 

 of these specimens. One shows no trace of spermathecae, two show 

 parts of ducts but no sacs, and the others show from one to three 

 sacs with ducts, but never four. They are all at 9/10 and 10/11 in 

 line with setae c. A small collection is from a rotten log near Douglas 

 Ijake in the same county as above. Sections were made from tliree 

 specimens. One has a definite duct without sac at 10/11 and no 

 other traces, and the other two specimens show no traces of sperma- 

 thecae. Two specimens were sectioned from a collection made in a 

 rotten log at Macatawa, Allegan County, Michigan. One specimen 

 shows no traces of spermathecae, and the other one has a sac and 

 duct at 9/10 and a trace of a duct at 10/11 on one side and no traces 

 on the other. A collection was made under a rotting straw stack 

 near Fremont, Steuben County, Indiana, a few miles from the Michi- 

 gan State line. Two of four specimens sectioned show no traces of 

 spermathecae. Another one shows a sac and duct at 9/10 on one 

 side. The fourth one has a small sac and duct at 10/11 on one side 

 and no traces of others. 



The aberrant specimens are indistinguishable in other ways from 

 the normal ones and presumably have come from the same parents 

 or immediate ancestors. They are very similar to H. norvegicus of 

 Europe, which Michaelsen has suggested may have arisen through 

 retrogression from H. constrictus. I have hesitated to identify the 

 American specimens with H. norvegicus since they differ slightly, and 

 I do not know that there is evidence of such close association between 

 the two European forms. H. norvegicus is described by both Eisen 

 (1874 : 48) and Michaelsen (1902 : 6) as having the clitellum on 26-32, 

 and the tubercula pubertatis as commonly including 31. In the E. 

 tenuis specimens with spermathecae which I have examined, the cU- 

 tellum very uniformly extends only to the anterior edge of 32, and 

 the tubercula pubertatis includes only 29 and 30. The only excep- 

 tion is a Burt Lake specimen which has not been sectioned but which 

 has the clitellum on 26-32 and the tubercula pubertatis of one side 

 on 30 and 31. None of the H. tenuis material from the other parts of 

 North America outside of Michigan and its immediate vicinity are 

 known to develop any traces of spermathecae. 



All of the species of the subgenus Bimastus found in North America 

 with the exception of H. tenuis are presumably indigenous and form 

 65008°— Proc.N M.vol.52— 17 12 



