14 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 50. 



The prevulvar portion of the body, or the esophageal portion, is 

 equal in length to a little more than one-sixth of the entire body 

 length. The head is rounded and is 20 to 22 ]j. in diameter. From 

 the head the body enlarges gradually to the posterior end, which is 

 rounded or bluntly conical. In mature females the cuticle is usually 

 smooth for a short distance posterior of the head and is then trans- 

 versely striated, the striations showing in profile as serrations in 



some cases, but usually 

 presenting the appear- 

 ance of hemispherical 

 beading (figs. 10 and 

 13). The vulva (figs. 

 12 and 13) is ventral, 

 just posterior of the 

 posterior termination 

 of the esophagus, and 

 forms a transverse slit 

 at the summit of a more 

 or less prominent cone. 

 The portion of the body 

 following the vulva is 

 marked for a distance of 

 3 to 1 mm. by a series of 

 irregularly arranged, 

 hemispherical to fungi- 

 form cuticular eleva- 

 tions (figs. 14 and 15) 

 in three or four rows 

 along the ventral sur- 

 face. These elevations 

 are usuall}^ conspicu- 

 ous; in the freshly col- 

 lected worms they are 

 clear and refractive h}'^- 

 aline structures, but in 

 alcoholic material the}'^ 

 are often dark and in one gtycerin mount they are a reddish brown ; 

 they are round to oval in shape and 4 to 13 [x in diameter. Another row 

 of smaller inconspicuous elevations, about 2 [ji, in diameter, may be seen 

 in the vicinity of the vulva, extending for a short distance anteriorly 

 and posteriorly (fig. 15). The uterus extends to the posterior end 

 of the worm and then turns forward, the uterus and ovary forming 

 a series of loops with the long axis parallel, in a general way, to that 

 of the worm (fig. 16). The eggs (fig. 17) are strikingly variable. 



Fig. 10.— TKicno.soMoiDES crassicauda. Young female with 



MALE IN VAGINA. ENLARGED. AFTER VON LiNSTOW, 1874. 



