Oligochaeta 



5a 



developed ovaries and of oviducts is present in 10 in one specimen; two have 

 small ovaries and either a pair of oviducts or a single one in 10; one has small- 

 ovaries and no oviducts in 10; and three specimens have neither ovaries nor 

 oviducts in that somite. But two specimens are in the proper stage of sex 

 organ development to show spermathecae, and in. one of them these organs are 

 paired in 11 and 12 and there is a single one in the right hand side of 10 (fig. 1). 

 In the other specimen spermathecae are paired in 9, 11,. and 12, there is one 

 on the left side of 10 and two on the right side of that somite (fig. 2). As' will 

 appear in the general discussion of this species, the collections contain an un- 

 usually large percentage of specimens with partially or well developed sex organs. 

 Such individuals are ordinarily very rare. The diameters of these specimens 

 are 1-1 -4 mm^ 



Lumbriculus inconstans (F. Smith.) 



Length, 30-60 mm. Diameter, ■ 6-0 • 8 mm. Number of somites, 150-200, 

 or more. Colour in life, reddish, anteriorly greenish. Prostomium rounded, 

 length one and one-half times the basal width. Spermiducal pores usually 

 on 10, occasionally on 9 or 11. Oviducal pores usually two pairs in two somites, 

 next following the one with spermiducal pores, occasionally but one pair. 

 Spermathecal pores paired or asym,metrically distributed on four or five somites; 

 posterior to the atrial somite. Spermaries and spermiducal funnels one to 

 three pairs, comrhonly two pairs in 9 and 10. Ovaries and oviducal funnels 

 one or two pairs, commonly two pairs in 11 and 12. Spermathecae paired or 

 asymmetrically distributed in four or five of somites 11-16. 



A few specimens of this species were found associated with L. variegatu^ 

 in the collections from the following localities: Cellinson point, Alaska, June 13, 

 1914, in mud iji tundra pond (margin). Herschel island, Yukon Territory,^ 

 July 30-31, 1916, pond in tundra swamp at east end. 



Fia. 3 



Diagram showing distribution of reproductive organs in a specimen of, Lumbriculus inconstans. 

 Numerals and letters as in figs. 1 and 2. 



But two of the specimens of L. inconstans have atria. One of them has 

 paired atria in 10, but no traces of spermathecae. It has also paired spermaries 

 and spermiducal funnels in 9 and 10, paired ovaries and oviducts in 11, one 

 well developed ovary and one minute one in 12, but no oviducts are recognizable 

 in that somite. Small cell aggregates that are apparently similar to rudimentary 

 ovaries are present on one side of 13-17. Similar bodies were found by Mrazek 

 (1907:429) in L. variegatus. Another specimen that is more nearly mature 

 has also paired atria in 10 (fig. 3) and paired spermaries and spermiducal funnels 



46455—21 



