50 



Lumbrimlus inconstans (Smith). 



In life reddish, anteriorly greenish. Prostomimn rounded, 

 length li times the basal width. Spermiducal pores on X (excep- 

 tionally on XI). Two pairs of oviducal pores, XI/XII and 

 XII/XIII. Spermathecal pores on XI — XV or XII — XVI. Brain 

 anteriorly, but slightly, concave, posteriorly with a deep, round- 

 ed trilateral incision. Contractile csecal transverse appendages 

 of the dorsal vessel beginning in XI, becoming larger and more 

 branched in succeeding somites. Two pairs of testes and two 

 pairs of spermiducal funnels in IX and X. Atria pyriform, 

 one pair in X (exceptionally in XI). Two pairs of ovaries and 

 two pairs of oviducal funnels in XI and XII. Five pairs of 

 spermathecsein XI — XV or XII — XVI. Nocopulatory (albumen) 

 gland. Length, 30 — 60 mm. Diameter, .6 — .8 mm. Number of 

 somites, 150 — 200, or more. 



If the above disposition of the two species under discussion 

 be correct, and if the views of Michaelsen (1902) concerning 

 the phylogenetic relationships of the lumbriculid genera are 

 well founded, the species inconstans seems to have the more 

 primitive condition of spermiducal structures, and L. variegatus 

 may have been derived from it by the disappearance of the ante- 

 rior pair of testes and of sperm-ducts and a reduction in the num- 

 ber of anterior somites. The specimen of L. inconstans referred 

 to above, in which the spermiducal pores are on a somite pos- 

 terior to the somites containing the testes, presents a condi- 

 tion normal to families higher than the Lumbriculidw but not 

 ordinarily found in that family. 



The transfer of the American species from the genus 

 Trichodrilus to Lumbriculus leaves the former genus much 

 more homogeneous and simplifies its definition. 



University of Illinois, December 16, 1905. 



