68 NORTH AMERICAN 



Note : There is some doubt as to whether this species should be as- 

 signed to the genus Oncholaimellus for the following reasons: There are 

 no pharyngeal teeth. The amphid varies somewhat from that of the type 

 species. The spicula are of equal size, whereas in the type species orie of the 

 spicula is only half as long as the other. 



CEPHALOBUS.. Bastian, 1865. 

 Fig. 22, Plate VIII. 



5i. 



1 8 15 23 '61 04 

 19. Cephalobus sub-elongatus, n.sp. .6 mm. 



1.6 3. 3-6 4-3 2.1 



The thin, transparent, colorless layers of the naked cuticle are traversed 

 by about seven hundred plain, transverse striae, resolvable with high powers 

 without very much difficulty. The conoid neck becomes convex-conoid to- 

 ward the obscurely lobed head, which is rounded in front, and is set off by 

 an almost imperceptible, broad, exceedingly shallow constriction. There are 

 no cephalic setae, and no eye-spots ; no amphids have been seen. There are 

 three rather distinct, bluntly conoid lips, which are rounded in front, each 

 of which apparently has two inconspicuous innervated papillae. The open 

 vestibule leads to a conoid pharynx, which is about one and one-half times 

 as long as the lip region is wide, and tapers from front to back in a com- 

 paratively uniform way. Between the lips it has a width about one-third as 

 great as that of the lip region. The posterior half of the pharynx rests in 

 the anterior end of the oesophagus, which enlarges very perceptibly, so that 

 a little behind the base of the pharynx it is more than half as wide as the 

 corresponding portion of the head. It continues to have relatively much 

 the same width until near the middle, where it is about three-fifths as wide 

 as the middle of the neck. There it suddenly diminishes in size so as to be 

 only one-fourth to one-fifth as wide as the corresponding portion of the 

 neck. Passing through the nerve-ring with this narrow diameter it finally 

 enlarges to form an ellipsoidal cardiac bulb about two-thirds as wide as the 

 base of the neck, containing a rather distinct triplex but not very complex 

 valvular apparatus of the form usually seen in this genus. There is no very 

 definite cardia. The intestine, which is separated from the oesophagus by 

 a rather broad and shallow constriction, is at first only half as wide as the 

 corresponding portion of the body. It soon becomes thicker walled, and 

 enlarges so as to be three-fourths as wide as the corresponding portion of 

 the body. It is composed of cells of such a size that probably only about 

 two are required to build a circumference. The contents of the cells are not 

 distributed so as to give rise to anything distinct in the way of tessellation. 

 The posterior lip of the anus is very slightly elevated. From the anus the 

 rectum, which is somewhat longer than the anal body diameter, leads inward 

 and forward. The rectum is separated from the intestine by a rather dis- 

 tinct constriction. The tail is at first convex-conoid, the convexity existing 



