58 NORTH AMERICAN 



cated just behind the base of the pharynx. The duct which leads to it seems 

 to be destitute of an ampulla. 

 40 



1.9 10.2 21.4 -M- 92. 



_ - 2.1 mm. 



1.2 2.2 2.8 2.5 1.8 



In front of the anus there is a series of about fifty pairs of oblique 

 copulatory muscles, whose presence is indicated by the oblique groups of 

 granules in the cuticle. The ejaculatory duct is about one-third as wide as 

 the body. The blind end of the anterior testicle is about twice as far behind 

 the base of the neck as this latter is behind the anterior extremity. 



Habitat : Fresh water ponds, Cape Breton Island, Dominion of Canada. 

 Sublimate to balsam. 



DOLICHODORUS, n.g. 

 Fig. 16, Plate VI. 



58 



14. Dolichodorus heterocephalus, n.sp.' 3 (34) 7 '* 9 '* ' 52 ' 97 ' 2 3. mm. 



.6 (i.i) 1.6 1.7 2.1 1.2 



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

 by transverse striae resolvable with high powers under favorable conditions 

 into rows of exceedingly minute, somewhat irregular elements. This reso- 

 lution is not at all difficult in specimens which are moulting. Under these 

 conditions scales of the outer cuticle sometimes survive, readily resolvable 

 into refractive transverse markings between which are the small elements 

 mentioned. Ordinarily at first glance, the cuticle appears to be merely re- 

 solvable into transverse striae which are somewhat roughened on the edges 

 of the dividing lines. The conoid neck ends in a head which has a very 

 prominent lip-region set off by a very prominent and deep constriction. The 

 front of the head is rounded, and the constriction separating the lip-region 

 from the remainder of the head is of such a nature that the contour of the 

 lip-region, when seen in optical longitudinal section is somewhat elliptical, so 

 that the lip-region has the form of an ellipsoid of rotation. The depth of 

 this figure is about equal to half its width. No papillae have been seen on 

 the lips, but minute papillae might readily be present without having been 

 observed. No traces of amphids have been seen. There are no eye-spots. 

 The vestibule is exceedingly narrow and closely surrounds the apex of the 

 very slender narrow spear. This latter extends nearly half-way to the an- 

 terior border of the median bulb and is long and slender like that of 

 Trichodorus. The oesophagus at the base of the spear is a tube about one- 

 third as wide as the corresponding portion of the neck, and continues to have 

 this diameter until it expands suddenly to form the elongated median bulb, 

 which is three-fourths as wide as the corresponding portion of the neck and 

 fully twice as long as wide and is armed internally with a conspicuous, ellip- 

 soidal, rather simple valvular apparatus nearly half as wide as itself. When 



