240 



NEMATODES OF THE GENUS PHTSALOPTERA, 



distended portion of the common trunk, varjdng in length from .72 to 1.2 mm., 

 and in width from .144 to .288 mm. 



The vestibule is always long, though its length is often concealed in sinuous 

 folds which make exact measurements difficult. Its leng-th varies quite irregularly 

 from .90 to 1.8 mm. and the common trunk shows similar variations, irrespective 

 of the size of the worm, from 1.44 to .720 mm. The diameters of vestibule and 

 common trank vary from .064 to .112 mm., the maximum width being due to the 

 presence of eggs, but the vestibule is always slightly wider than the common trunk 

 of the same specimen. The two branches into which the common trunk divides 

 are very narrow, .06 to .08 mm., and slightly unequal in length, their respective 

 lengths varying from .144 and .192 mm. througli all intermediate lengths to .480 

 and .544 mm. After the second forking, the four slender branches connect with 

 the four uteri at distances varying from .640 to 1.56 mm. in different individuals. 



Figs. 20-30. Physalopttera antarctica var. , typica, and var. laita. 



20.Var. iypica, 20 mm. female; v., vulva; 21. Var. lata, 14 mm. female; 22. 

 Var. lata, 18-6 mm. female; 23. Var. typica, and 24. Var. /a/c— dorsal view of 

 anterior end, showing position of cervical papillae, nerve-ring and junction of 

 muscular and glandular oesophagus (x 20) ; 25. Var. typica, 26. Var. lata, 22 

 mm. females, — posterior end (x 6-3) ; 27. Tail of female, var. typica, same 

 specimen as shown in fig. 20 (x 20) ; 28. Tail of 31 mm. female, var. lata (x 20); 

 29. Internal face of lip, var. lata (x 116) ; 30. Dorsal view of lip, var. lata (x 

 116). 



The uteri in the older specimens are crowded with eggs and attain a maximum 

 width of .35 mm., smaller and younger specimens having pi-oportionally narrower 

 uteri, only. .08 mm. wide when quite immature. The reeeptacula seminis are 

 marked off from the oviducts by deep constrictions, but pass gradually into the 

 iiteri (Text-fig. 19), the diameter of uterus at the junction being .128 mm. and 

 of oviduct .048 mm. The reeeptaculum seminis, in its maximum development, 

 measures .480 mm. in length, and .288 mm. in diameter; the oviducts 1.6 to 1.8 

 mm.; the ovaries about 9.5 mm 



