Article V.— Notes on Species of North American Oligochwta.V. 

 The Systematic Relationships of Lumbriculus (Thinodrilus) 

 ineonstans (Smith). By Frank Smith. 



When this species was described by the writer (1895) it 

 was thought that the differences between it and previously 

 described species were such as to warrant the recognition of a 

 new genus; hence the genus Thinodrilus. Michaelsen in his 

 great work on the Oligochceta (1900) saw fit to include thisspecies 

 in the genus Trichodrilus Claparede with the two European 

 species. Recent papers on the reproductive organs of Lumbric- 

 ulus variegatus (Miiller) by Wenig (1902) and Hesse (1902) 

 have extended our knowledge of that species and have shown 

 that it is in some particulars very similar to Thinodrilus in- 

 eonstans, and as it now seems to the writer that there is more rea- 

 son for including the latter species in the genus Lumbriculus 

 than in the genus Trichodrilus, it will be referred to in the fol- 

 lowing discussion as Lumbriculus ineonstans. 



We will first consider the chief points in which L. ineonstans 

 differs more from L. variegatus than from the two species of Tri- 

 chodrilus (T. allobrogum Claparede and T. pragensis Vejdovsky ). 



Albumen Gland. — An albumen orcopulatory gland, which 

 is described and figured by Vejdovsky (1884) as occurring in 

 somite IX in L. variegatus, is lacking in Trichodrilus and in L. 

 ineonstans. No reference is made to such an organ by Wenig 

 and Hesse in their recent papers on L. variegatus, and Michael- 

 sen (1903, p. 60) has recently raised the question as to its oc- 

 currence, and queries whether the structures seen by Vejdov- 

 sky may not have been rudiments of efferent reproductive 

 organs. It should not be overlooked that the structure of the 

 albumen gland is described by Vejdovsky (1884, p. 149 I as simi- 

 lar to that of the spermathecie, and that Wenig (1902) de- 

 scribes and figures a single spermatheca in IX but makes no 

 reference to an albumen gland. Vejdovsky used the presence 



