THE MONONCHS 



56. M. brachylaimus, n. sp. There are two exceedingly minute, almost invisible, 

 apparently rudimentary, ventrally submedian, conical, forward-pointing toothlets at 

 the base of the pharynx. These are not shown in the illustration. Three slightly 



2.4 7. 21. 65 14 



10 it 



(fee 



2.4 



2.3 



2.4 



7.4 



2,8 



19. 



94. 

 1.9 



94, 



2.5 2.5 



> 3.5 m 



arcuate, duplex, longitudinal ribs 

 strengthen the walls of the phar- 

 ynx and reach from end to end, 

 one being dorsal, the other two 

 ventrally submedian. Amphids 

 difficult to see. (Esophagus at 

 first slightly expanded. The ces- 

 ophageal lining is not so promi- 

 nent as in many other species; its 

 optical section finds expression in 

 3 or 4 parallel lines, occupying 

 about one-fourth of the longitu- 

 dinal optical section. There is an 

 inconspicuous, flattish cardia. In- 

 testine about 8 to 12 cells in girth, 

 faintly tessellated. The tail is 

 conoid to the plain, unarmed con- 

 oid terminus. The base of the spinneret is about one-fifth as wide as the base of 

 the tail. The clavate caudal glands form a close tandem in the anterior third of 

 the tail. The anus has rather conspicuous, with well developed, though not protrud- 

 ing lips. There is a pair of innervated lateral papillae near the middle of the tail of 

 the female. Both in front of and behind the vulva, especially behind, there are 

 inconspicuous papillae, occupying a distance equal to twice to thrice the length of 

 the body-diameter. The two equal, arcuate, rather slender spicula are one and 

 one-half times as long as the anal body-diameter, and are of nearly uniform size 

 throughout the greater part of their length. However, beginning near the slightly 

 truncated tips they taper slightly in the distal sixth. The proximal ends are also 

 narrowed slightly and lie well toward the dorsal side of the body, at any rate when 

 the body is incurved. The two accessory pieces, each about two-thirds as wide as 

 the spicula, are located opposite the distal portions of these latter. When seen in 

 profile they appear to lie nearly at right angles to the body axis, and seem to cross 

 the distal parts of the spicula. They are about two to three times as long as wide, 

 and their distal extremities are diminished and bifurcated, the two prongs of the 

 fork forming a U-shaped figure. When at rest these accessory pieces, as usual, 

 are well inside the anus, in fact appear as if lying immediately under the lateral 

 fields. In front of the anus there is a uniform series of about 16 equidistant, 

 closely approximated, innervated supplementary organs, occupying a distance about 

 equal to the length of the tail. When the tail end of the body is incurved, each 

 organ appears on the ventral contour as a flattish cone, at the apex of which is a 

 nerve ending, which from this point extends inward and forward. 



Brown, sandy soil, Arlington Farm, Virginia, U. S. A. This nemativorous 'mon- 

 onch is distinguished from all others by the relative broadness of the pharynx, 

 and by the position and size of the basal onchi. Especially well adapted to show the 

 structure of the lip muscles and other organs of the head. Fig. 67. 



