60 NORTH AMERICAN 



as this latter is behind the anterior extremity. Near its blind end its diam- 

 eter is about one-half as great as that of the body. The spermatozoa art 

 small and numerous and it appears that the reduction divisions take place in 

 a short segment of the testis not far from the blind end. 



Habitat: Freshwater, Douglas Lake, Michigan. Silver Spring, Florida. 

 Female, Flemming solution to glycerine; from Florida. Male, from Michi- 

 gan, sublimate to balsam. 



CYATHOLAIMUS, Bastian, 1865. 



Fig. 17, Plate VI. 



26. 



15. Cyatholaimus truncatus, n.sp. : : 1.6 mm. 



1.8 2. 2.1 3.3 2.1 



The moderately thick layers of the transparent, colorless, naked cuticle 

 are traversed by about fifteen hundred transverse striae, resolvable into 

 transverse rows of distinct dots, which are not very materially modified in 

 the lateral fields. The slightly conoid neck ends in a truncated head, whose 

 lip region is set off by an almost imperceptible expansion. The cuticle be- 

 comes somewhat thicker toward the head, and the dotlike markings more 

 distinct and refractive. Beginning near the head and ending near the spin- 

 neret there are circular markings arranged in somewhat irregular rows 

 along the lateral fields. The longitudinal distance between these markings 

 near the middle of the body is a little greater than the radius of the body, 

 and the diameter of the circles is somewhat greater than the width of one 

 of the annules, sometimes twice as great. These markings are not all of the 

 same size, some being nearly twice as large as others.* The lip region is 

 twelve-parted, and there are twelve longitudinal chitinous structures sur- 

 rounding the vestibule. These no doubt indicate the infolding of the lips 

 when closed. Probably the best conception of the lip region is expressed by 

 saying that there are six lips, each two-parted, but that the divisions are all 

 very similar to each other. On the front of the lips there are six forward 

 pointing innervated papillae arranged in the usual position. Along the outer 

 margin of the head there are ten acute, tapering, cephalic setae, two lateral, 

 and four submedian pairs. The longest of these setae are about equal to 

 the radius of the head. According to the position of the lips these setae 

 vary in attitude. They may be folded together on the front of the head so 

 as to be in the position of the spokes of a wheel, but they may point 

 forward when the mouth is partly open, and are in a somewhat spreading 

 position when the mouth is wide open. The pharynx is on the whole con- 

 oid, and about three-fourths as deep as the head is wide. Springing from a 

 little behind its middle is a strong, conical, acute, forward pointing dorsal 

 tooth, the ventral contour of which lies approximately in the axis of the 



*The two most pronounced rows are nearly opposite the edges of the lateral fields, 

 but there is an irregular median row. 



