2d4 NEMATODES OP THE GENUS PHYSALOPTERA^ iii. 



fig. 23). The nerve ring broad, surrounding the muscular oesophag-us just above 

 the junction. Total length of oesophagnis one-tenth of the body length in the 

 longest individuals (43 mm. specimens), becoming relatively longer as the length 

 of the body decreases, i.e., in the younger specimens, though the relative increase 



Fig-s. 1-6. Pliysaloptera antarctica var. tijpica. 



1. Anterior end of male, showing oesophagus (x 15) ; e.p., excretory pore, 

 n., nerve ring; 2. Junction of oesophagus and intestine (x 48); 3. Lateral view of 

 anterior extremity (x 125) ; 4, Internal face of lip (x 190) ; 5. Male spicules 

 (x 48) ; 6. Portion of posterior region of male, showing spicules and ductus 

 ejaculatorius (d.e.), (x 27). 



is not constant, and the length is found to vary slightly in specimens of the same 

 size, from one-seventh to one-eighth of the body length in males and females 23 

 to 28 mm. long. The base of the oesophag\TS is broadly pointed, and inserted 

 into the middle of the wide intestinal lumen, where the narrow entrance to the 

 oesophag-us is protected by valves (Text-fig. 2). Intestine slightly wider than 

 oesophagus, usually straight, occasionally sinuous, or with a single loop. 



Males (Text-fig. 7) 10 to 28 mm. long, diameter in middle of body .45 to 

 .78 mm., diminishing a little in front of caudal wing's. Cloaca at a distance of 

 one-fourteenth to one-twenty-third of the body length from the tail point, the 

 distance not having a constant relation to the total length, but varying in 

 specimens of the same length. Tail deeply excavated and curved ventrally; 

 lateral alae ample, very wide anteriorly, .32 to .45 mm., narrowing rapidly to- 



