258 ORDER ISOLAIMIA 



40. Pycnolaimus pygmaeus n. sp. *? 6 - TJ 7.7 4.9 ' " Cuticle thin 

 naked. Near the middle of the body the very narrow, exceedingly minutely 

 crenate wings occupy a space about equal to the width of two annules of the 

 cuticle. Neck conoid. From the amphids an internal element extends inward 

 and backward a distance twice as great as the width of the corresponding portion 

 of the neck. Lip-region difficult to decipher. Cephalic cuticle very thick, espe- 

 cially near the base of the lips. When the head is viewed in profile and in optical 

 section there are seen connected with this thickened portion of the labial cuticle 

 elements that extend forward over the vestibule. At first sight these extensions 

 appear to be thin, cutinized flaps, that are very minutely transversely striated. 

 A careful examination, however, appears to indicate that they may have some- 

 what the structure of odontia, inasmuch as a short distance behind the apices, 

 which are decidedly sharp, the inner contours curve in toward the axis of the 

 head, and the longitudinal section of the elements, including the bases, above 

 described, appear claw-shaped. The dorsal and ventral elements, thus viewed, 

 are very much alike. Concentrating attention on either lateral surface of the 

 head one finds, opposite the axis, two elements which extend forward parallel 

 to each other and then bend toward the axis, arching inward to meet the dorsal 

 and ventral elements already described, and appear to be the median elements 

 of lateral labial organs. These elements are not so finely striated as the labial 

 elements first mentioned, and appear to be slightly darker. The napiform 

 vestibule leads to the pharynx, the entrance to which seems to be nearly closed 



mnd by a very slight curvature on the anterior part of one of the cutin- 

 ous elements marking its contour. The oesophagus diminishes 

 , . slightly in diameter as it passes backward, so that its middle part 

 1 is hardly two-fifths as wide as the corresponding portion of the 

 neck. It then diminishes more rapidly, so that just in front of the 

 aw Jw?S"* cardiac bulb it is only about one-third as wide as the corresponding 

 spn jfeJ x75o portion of the neck. There is no vestige of a median bulb. Cardiac 

 bulb somewhat pear-shaped, or sub-spherical, three-fifths as wide as the base of 

 the neck, and containing a rather complex central valve half as wide as the bulb 

 itself. Two small, refractive elements occur one in front of the other in the midst 

 of the valve. There is a sub-spherical cardia one-third as wide as the base of 

 the neck. The intestine becomes at once three-fourths as wide as the body; 

 its cross-section presents apparently only two cells. These cells contain granules 

 of various sizes and kinds; the largest and clearest are spherical, and have a 

 width two to three times that of one of the annules of the cuticle. The smaller 

 and darker granules are not distinctly spherical and vary in size down to those 

 of very minute size. From the inconspicuous but very slightly raised anus, the 

 refractive rectum extends inward a distance a little greater than the anal body- 

 diameter. The tail is conoid from the anus, but is convex-conoid at the termi- 

 nus. The description is derived from a specimen much too young to give any 

 indication as to the position and form of the sexual organs. The measurements 

 must be correspondingly interpreted. 



Habitat: From green-house soil, Ann Arbor, Mich., U. S. A. Fixed in Flem- 

 ming; examined in water. Fig. 40. 



41. Isolaimium papillatum n. sp. Cuticle rather thin, naked. Neck convex- 

 conoid anteriorly. Cuticle with surface innervations along the edges of the 

 lateral field. Nerve-ring oblique. Pharynx tubular, one-sixth as wide as the 

 head measured opposite its base. Tail of the male conoid, slightly arcuate, a 



