SUBGENUS IOTONCHUS 



(S. S.479) 177 



.._ on? 



54. M- studeri Steiner. Wall of the pharynx presenting 5 longitudinal ribs, 

 four of them in 2 pairs, the fifth single. At the base of the pharynx numerous 

 small denticles, arranged in rows of from three to four. (Esophagus powerful. 



2.8? ? 26. 67. 94. . A little in front 



? ? ? 3.4 ? O f the posterior 



2.8? ? 27. H 95.4. end of the cesoph- 



? ~ ? 3TI Te^ ' agus there are 3 

 powerful teeth which, according to Steiner, "are 

 similar to those seen in Mononchus dolichurus." 

 Tail of the male arcuate, conoid to the spinneret, 

 which is about one-fourth as wide as the base. The 

 three caudal glands form a tandem series in the an- 

 terior half of the tail. The slightly arcuate spicula 

 in their widest part are about one-sixth as wide as 

 the corresponding portion of the body. They taper 

 slightly at either end, and are about one and one- 

 third times as long as the anal body-diameter. They 

 are not cephalated. The accessory pieces appear to 

 be of the usual character. The twelve short, tubular, 

 equidistant supplementary organs, occupying a space equal to twice the length of 

 the tail, do not interfere materially with the ventral contour. The internal tubular 

 parts are about as long as the spicula are wide. Distance from the anus to the 

 posterior supplementary organ is nearly twice as great as the distance between the 

 adjacent organs. Two pairs of post-anal papillae were noted. 



Found on the island of Ufenau in the Zurich Lake, under moss. Fig. 65 (after 

 Steiner). 



55. M. zschokkei Menzel. This species, one male to each three to four females, 

 is found in various parts of the Austrian and Swiss Alps. Neck and oesophagus 

 3.? ? 25. '66' 95. 



25. 



3.4 

 96. 



2.4-3.5 mm 



denticles 



? ' ? 3.6 2.4 



tapering but little. Small 

 often occur at the base of the pharyn- 

 geal cavity. Uterus capable of con- 

 taining one or two eggs. The blunted 

 terminus of the conoid arcuate tail is 

 about one-eighth as wide as the base. 

 The slightly arcuate spicula are rather 

 slender, each, however, having a stif- 

 fening piece in its distal half. Acces- 

 sory pieces as figured by de Man for 

 his M. brachyuris Butschli. Beginning 

 near the anus the 21 projecting, ob- 

 liquely conical, equidistant, contiguous 

 supplementary organs, each as high as 

 wide, occupy a space 3 times as long 

 as the tail. 



Found in the high Swiss Alps. Fig. 

 67, after Menzel, who considers that 



of'all the European mononchs at present known, zschokkei has close affinity only 

 with M. parvus de Man, from which it differs in the position of the onchus and 

 the relative abundance of males. 



