154 (S- S. 466) 



THE MONONCHS 



? 



20. 



? 

 M ? 



- 3.6 an 



larger than in muscorum. Striae very difficult of resolution. Found about the 

 roots of pitcher-plants and tamarack, in a swamp, Wisconsin, U. S. A. The differ- 

 ence between this and muscorum may not be very important. Both are nema- 

 tivorous. Flemming mixture to glycerine. Fig 39 (at bottom previous page). 



25. M. spectabilis Ditlevsen. The muscular oesophagus encompasses the proxi- 

 mal third of the pharynx, and has a conspicuous lining. The uteri may contain 



? ? 20. '55' 96.8 , __ from 2 to 4 eggs, 

 usually 2. The 

 acute conical tail 



? ? ? is strongly arcu- 



ate. The male is a little more slender than 

 the female, and increases in size from a point 

 where the supplementary organs commence, in 

 such a way that the body assumes a maximum 

 circumference near the anus. The copulatory 

 muscles are strongly developed, and the num- 

 erous, prominent, supplementary organs appear 

 to have a subventral position, forming two 

 longitudinal rows, between which is a groove. 

 Fourteen of these supplementary organs are 

 figured by Ditlevsen manifestly not the whole 

 series. The arcuate spicula, which have a 

 strengthening piece in their distal halves, are 

 about one and one-half times as long as the 

 anal body-diameter. Their proximal ends are 

 not cephalated. At the widest part, toward 

 the proximal end, they are about one-fifth to one-sixth as wide as the body ; thence 

 toward the distal end they taper gently. The obscurely bifurcated accessory pieces, 

 which in profile view appear to cross the spicula, are of the usual form, and are 

 about one-third as long as the spicula, and about one-third to one-fourth as wide as 

 long. Their distal extremities lie somewhat in front of the tips of the spicula and 

 toward the ventral side of the body. The elongated eggs are nearly one and one- 

 half times as long as the body is wide, and less than half as wide as long. 



Numerous specimens, the males as numerous as the females, found at Hellerup, 

 near Oresund, Denmark. This species exhibits the phenomenon of flotation. Dit- 

 levsen says : "If some material (meadow soil) is spread in a flat glass cup and 

 water is poured over it, the mononchs will mount rapidly and be lying on the sur- 

 face dry and shining." Fig. 40 (after Ditlevsen). 



26. M. index Cobb. No striae seen. The .neck diminishes opposite the base of 

 the pharynx to form a rather cylindrical, truncated head which is slightly expanded 

 at the lip region. Amphids, one-fifth as wide 2.1 8.8 30. *69 15 95. 6 N 



as the head, are indicated by transverse mark- 2.4 3.2 3.5 3.6 2. 

 ings, bent backward at each end, and located opposite the middle of the dorsal 

 tooth. Denticles in about five rows, the outer rows more distinct. Pharynx half 

 as wide as the head, and about three times as deep as wide. CEsophagus more or 

 less conoid, with a massive lining occupying about one fourth of the optical sec- 

 tion. Cardia pointed. Intestine few cells in girth; rather obscurely tessellated. 

 Rectum half as long as the anal body-diameter. Longitudinal fields are visible 

 throughout most of the length, and are about two-fifths as wide as the body. The 

 diameter of the body increases somewhat just in front of the anus, and then dimin- 

 ishes suddenly at the anus, so that the beginning of the tail is very considerably 

 less in diameter than the portion of the body immediately in front of the anus. 



