FREE-LIVING NEMATODES 33 



terior parts of the spicula is greater than in Thoracostoma setosum, Linst. The 

 strong, chitinous framework is strengthened by a middle piece in the distal three- 

 fifths. The two separate, strong, rather stout accessory pieces are bent a very 

 little, and are half as long as the spicula. They are of somewhat irregular width, 

 but appear when seen in profile about twice as wide as the dorsal cuticle is thick. 

 They lie parallel to the spicula, but their cephalated proximal ends, a little wider 

 than those of the spicula, are bent away a little and lie somewhat to the dorsal side 

 of the body-axis. 



The elevated, mammiform supplementary organs, about one-sixth as wide 

 as the body and half as high as wide, are arranged in ventrally submedian rows 

 one and two-thirds times as long as the body is wide, the posterior members being 

 located a distance in front of the anus equal to one and two-thirds times the length 

 of the spicula. They are a little farther apart posteriorly than anteriorly, the 

 longest space being about equal to the length of the radius of the body as seen 

 in profile at the corresponding part. In addition to these two rows of five organs 

 each there is a single ventral organ a little in front of the middle of the spiciila, 

 similar in size and form to the others, but manifestly of a different structure. 

 Sometimes there is an appearance as if a rudimentary sixth ventrally submedian 

 organ is present in front of the fifth. Oblique copulatory muscles are arranged 

 close together coextensive with the supplementary organs. The ejaculatory 

 duct is about one-fifth as wide as the corresponding part of the body. 



Habitat; remarks. Bay, Cape Royds; Cape Royds. Three females and two 

 males, in good condition. 



February, 1914. 



