236 NEMATODES OF THE GENUS PHYSALOPTEEA^ iii. 



The peduncles of the first pair (from the caudal extremity) measure .078 mm., 

 the others .081 and .111 mm. respectively. They are situated in the midregion 

 of the tail, the most posterior .512 mm. from its extremity, the other two at dis- 

 tances of .768 and .864 mm., in a specimen 28 mm. long, where the cloaca! 

 aperture is 1.8 mm. removed from the tail point. 



The spicules are both short, and only slightly unequal, the right about three- 

 fifths the leng-th of the left. The left is straight and very slender, the right 

 cui-ved and stouter, indented near the distal extremity, and tapering to a point 

 (Text-fig. 5). It is commonly found nearer to the cloacal aperture than the left, 

 and often protruded for part of its length. The posterior portions of the single 

 genital tube are stout, deep-coloured, and clearly visible through the body wall. 

 The ejaculatory duct is infundibuliform, from 1.0 to 1.7 mm. long, and thickest 

 anteriorly where it is divided from the vesicula seminalis by a deep constriction 

 (Text-fig. 6). The vesicula seminalis is dilated just beyond the junction, and 

 then extends as a broad tube, of uniform width, usually straight forward to join 

 the vas deferens. Sometimes it is recurved at the anterior end, and the vas 

 deferens nins parallel with it for a short distance, before turning forward again. 

 The vesicula seminalis is from 2.4 to 3.2 mm. long, and the transition into the 

 vas deferens is marked by an abrupt narrowing. Vas deferens and the thread- 

 like testis may extend straight forward, towards the base of the oesophagus, or 

 be looped and coiled in the middle region of the body. 



Genitalia and caudal bursa are sometimes found already developed in speci- 

 mens only 10 mm. long, though most individuals of this length are still in the 

 larval stage. In a larva 14 mm. long, in which the posterior extremity is a little 

 withdrawn from the cuticle of the larval tail, caudal alae, papillae, and other 

 structures can he seen in an early stage of formation beneath the larval cuticle 

 (Text-fig. 9). On the other hand, many males are found in the adult stage at 

 a leng-th of 15 mm. Males of the largest sizes, over 20 mm. long, are rare, the 

 majority of the specimens being between 15 and 19 mm. long. In collection B, 

 which contains the only specimen 28 mm. long, the average length is 19 mm. 

 In collection C, in which the largest male is 20 mm., the average leng-th is 15 mm. 



Females (Text-fig. 20) 11 to 43 mm. long, diameter in middle of body .57 

 to 1.36 mm., diminishing to .25 mm. at the base of cephalic collarette, and to 

 .24 to .40 mm. at anus. Anus at a distance of one-sixtieth to one-fiftieth of the 

 body length from the posterior extremity in the larger specimens, sometimes 

 longer in the younger specimens, varying from one-fortieth to one-fifty-sixth 

 of the body length in specimens of leng-ths 25 mm. and under. Tail straight, 

 conical, and sharply pointed (Test-figs. 10, 27). Caudal pores diffieult to dis- 

 tinguish; only observed in a few specimens, opening in slight depressions in 

 the cuticle, .320 mm. from the extremity on a tail .768 mm. long. Vulva pro- 

 minent, always some distance behind the junction of oesophagus and intestine, 

 but varying in position from 1/3.0 to 1/4.9 of the body length from the anterior 

 extremity, the average distance being 1/3.8. Eggs very thick shelled and broadly 

 oval, measuring .051 x .040 to .044 x .033 mm. ; always containing embryos when 

 oviposited. 



Individuals of all lengths between maximum and minimum occur in collec- 

 tion B, but the intermediate leng-ths are most numerous. Only 3 specimens are 

 over 35 mm. long, and the average leng-th is 26 mm. Collection C contains 

 smaller and evidently younger specimens, the largest female being 30 mm. long, 

 and the average length 21 mm. A few very young specimens of the same type 

 and two or three adults, up to 27 mm. long, occur in collection A. 



