110 ASYMMETRY OF THE NEMATODE 



base of the pharynx. The oesophagus begins as a tube about half as wide as the 

 corresponding portion of the neck. It continues to have this diameter, or a 

 slightly greater, until near the middle of the neck it expands to form the median 

 swelling, which is nearly two-thirds as wide as the corresponding portion of the 

 neck, and has a distinct, simple, elongated, chitinous valvular apparatus, the 

 length of which is nearly equal to the corresponding radius of the neck. Behind 

 this bulb the oesophagus diminishes suddenly in diameter so that it is only one- 

 fourth as wide as the corresponding portion of the neck. It finally expands to 

 form the pyriform cardiac bulb, which is tw r o-thirds as wide as the base of the 

 neck, and contains a distinct, three-fold, more or less complicated, non-striated 

 valvular apparatus. The intestine becomes at once three-fourths as wide as the 

 body. There is an obscure flattish cardia a little more than one-third as wide as 

 the corresponding portion of the body. The cells of the intestine contain a few 

 scattered granules of variable size, the largest of which, fatty granules, are rela- 

 tively large and have a diameter nearly equaling that of the pharynx; the small- 

 est, probably of another character, being very much smaller. They are less 

 numerous and smaller toward the posterior part of the intestine. Xo doubly re- 

 fractive granules have been seen. The lining of the intestine is somewhat re- 

 fractive, so that, especially toward the middle of the body, the sinuous lumen is 

 often quite a distinct feature. The excretory pore is somewhat behind the middle 

 of the neck. The tail end begins to taper from some distance in front of the 

 anus, and tapers at about the same rate until after it passes the anus, where it 

 soon begins to taper more rapidly, so that the posterior somewhat concave conoid 

 half of the tail is relatively narrow, and the terminus itself hairfine. The diame- 

 ter of the tail at the middle is about one-sixth as great as at the anus. From the 

 rather prominent, salient, two-lipped vulva the vagina leads inward at right 

 angles to the ventral surface nearly halfway across the body. A mature ovum 

 is about as long as the body is wide, and fully one-third as wide as long, and there- 

 fore of such a size as to indicate that each uterus can probably contain only one 

 egg at a time. 



5.3 19. 28. 'M 45 - 88. 



4.4 5.5 6.3 6.5 4.8 ' The tail of the male is like that of his mate 

 in form and size, though it tapers more regularly. The two equal, uniform, long 

 and very slender, slightly arcuate, colorless, inconspicuous spicula are about two 

 and one-half times as long as the anal body diameter. Their proximal ends are 

 slightly cephalated by expansion. They are accompanied by a more plainly visi- 

 ble, simple, somewhat wider, slightly colored accessory piece w r hich is nearly 

 straight, and about half as long as themselves. Springing from a little in front 

 of the anus there is a very weakly developed or rudimentary almost invisible 

 bursa, whose somewhat asymmetrically arranged ribs or papillae, difficult of 

 observation, are located as follows : 



Almost exactly on the ventral line, in front of the anus, at a distance from it 

 equal to the corresponding body diameter, there is a circular marking (r, Fig. 

 1), which is larger than any other marking of this character, and seems to repre- 

 sent one of the male papillae. To the right of it, and a trifle behind it, rather 

 nearer the right submedian line, is another papilla of similar character, slightly 

 smaller. Opposite the anus, on the left submedian line, there is a small papilla; 

 the mate of this on the right submedian line (M), seems to be in the border of the 



