140 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



gus about 0.22 mm. in the male and 0.26 mm. in the female from the 

 anterior end of the body. 



The excretory pore is ventral and prebulbar in both sexes. In the 

 male it ranges from 0.96 to 1.45 (average 1.03) mm. and in the female 

 from 1.38 to 1.99 (average 1.63) mm. from the anterior end of the 

 body. The excretory pore is minute; it communicates with an oval- 

 shaped vesicle into which the excretory canals enter. The vesicle is 

 about 0.09 mm. in the male and 0.14 mm. in the female in length. There 

 are four excretory canals which emerge from the lateral line areas in 

 such a manner as to form an "X" with the vesicle at the junction. The 

 posterior canals are wider than the anterior. 



The esophagus is of the usual oxyurid type. It is of the same muscu- 

 lar structure throughout its length, except for the anterior cuticularized 

 end which projects into the buccal cavity. There is a slight bulge in the 

 esophagus about 0.05 mm. from its anterior end; from this point the 

 width remains the same, 0.043 mm. in the female and 0.036 mm. in the 

 male, to the slight constriction which marks the junction between the 

 esophagus and the esophageal bulb. The bulb averages 0.165 mm. in 

 the female and 0.125 mm. in the male in diameter. It contains a valvu- 

 lar apparatus, consisting in part of three cuticularized blade-like struc- 

 tures. The length of the esophagus, bulb included, ranges from 1.66 to 

 2.08 (average 1.84) mm. in the female and from 1.02 to 1.70 (average 

 1.43) mm. in the male. Thus it is nearly one half the body length of 

 the male and one third the body length of the female. 



Anteriorly the intestine is enlarged to a diameter greater than that 

 of the esophageal bulb. The diameter of the flask-shaped enlargement is 

 about 0.254 mm. in the female and 0.153 mm. in the male. From this 

 maximum size the diameter of the intestine gradually decreases to ap- 

 proximately 0.10 mm. in the female, slightly less in the male, which 

 is the size maintained throughout the remainder of its length. 



Male: The male reproductive system is composed of a single, coiled 

 testis which has a diameter of about 0.036 mm. The testis extends an- 

 teriorly to about the level of the intestinal bulb. An expanded region of 

 the testis connects with the seminal vesicle through an attenuated neck- 

 like portion. The seminal vesicle is about 0.40 mm. in length and has a 

 maximum diameter of 0.095 mm. 



The accessory reproductive structures (figs. 5 and 6) consist of the 

 spicule, accessory piece, and the genital papillae. There is a single spicule, 

 which ranges from 0.415 to 0.589 (average 0.496) mm. in length. The 



