RHINEMA 335 



114. Rhinema retrorsum n. sp. Cuticle thick, interrupted at twelve places so 

 as to form exceedingly distinct longitudinal wings, which when brought into 

 focus give a somewhat "fishbone "-like effect. The annules and their modifica- 

 tions give a retrorse appearance to the entire cuticle, but in reality the striae 

 are retrorse in the posterior part of the body, and the reverse in the anterior part. 

 Some of the cuticular markings cease in front of the anus on the male and are 

 not continued on the tail, so that the tail has a somewhat unusual appearance. 

 There are submedian longitudinal striations extending to the middle of the 

 tail. Neck for the most part cylindroid. Opposite the dorsal tooth there 

 is a distinct junction with the cuticle of the lip-region indicated by an almost 

 imperceptible constriction encircling the head. In front of this constriction 

 there are two others, close together, connected with the lip-region. Lips with 



outward-curved api- j. _io. ___. l''5?'l*_ J>i-* 



ces, surrounding a ^ 2 ' 8 3 " 



cyathiform cavity J-L _ M^J?^ r^n _ _?Ai- >" 12 ,. 



having a diameter 2 '- 9 3 ' 5 ^ ~* JUKSJH* , *,* 



about three-fifths as great as that of the front of J^Wlj/jj|| iH^JrifQfflfc 

 the head, and a depth not more than half that 

 amount. Into the midst of this shallow cavity the 

 dorsal onchium projects. Sometimes, however, this p/L. 

 cavity is deeper, namely, when the dorsal tooth is 

 withdrawn to a greater extent. Then the cavity 

 is about half as wide as the head, and about as deep 75 * lmlte 'apndal^Lpspn 

 as wide, and the lip-region is manifestly more closely folded. Onchium faintly 

 spear-like. Muscles of the pharynx of an entirely different character from 

 those of the oesophagus, which begins as a tube about half as wide as the cor- 

 responding portion of the neck, and continues to have this diameter until after 

 it passes through the nerve-ring, thereafter expanding gradually, but finally 

 somewhat faster, so that at the end it becomes two-thirds as wide as the base 

 of the neck. The posterior swelling is of such a character that one might speak 

 of it as a bulb. There is no very distinct cardia. Renette unknown. Vagina 

 reaching half way across the body. Mature ova at the flexure, ready to enter 

 the uterus, are one and one-half times as long as the body is wide and about half 

 as wide as long, with nuclei one-third as broad as themselves. The narrow ova- 

 ries are more or less cylindroid and contain comparatively few ova, apparently 

 arranged more or less single file. Anus of the male distinctly raised. Tail 

 arcuate and conoid to the naked terminus, which has a length about equal to 

 that of five of the preceding annules. Position of the caudal glands doubtful, 

 but it seems quite possible that they are located in the base of the tail. There 

 are a few inconspicuous hairs on the smooth terminus that are not shown in the 

 illustration, of which two have been seen in the ventrally submedian position, 

 having a length about two-thirds as great as the corresponding diameter of the 

 terminus. No supplements or special papillae or setae have been seen, though 

 it is possible that very small setae may have escaped observation. The slender, 

 slightly arcuate, rather uniform spicula have their proximal ends almost imper- 

 ceptibly cephalated by expansion. The uniform proximal three-fourths of the 

 spicula, when viewed in profile appear to have approximately the width of one 

 of the adjacent annules. In the distal fourths the spicula taper to an acute 

 point. There is a single, nearly straight but slightly "S "-shaped accessory 

 piece, two-thirds as long as the spicula, which is acute at its distal extremity 

 and capable of protrusion to a certain extent. It is fully as wide as the spicula. 



