TRIPLONCHIUM, APHELENCHULTJS 



301 



refractive nucleolus. Possibly this cell is the renette cell. The tail of the male 

 is a little more strongly developed than that of his mate. No pre-anal supple- 

 ments, though there appear to be one or two obscure papillae just in front of the 

 anus. There are very obscure, straight accessory pieces; these may be little 

 more than thickenings of the wall of the cloaca. The ejaculatory duct is two- 

 fifths, the vas deferens about two-thirds, as wide as the body. In glycerine speci- 

 mens the spermatocytes are distinctly refractive, ellipsoidal bodies, about one- 

 sixth as long as the body is wide. The dorso-ventral view of the amphids is very 

 instructive. As seen in glycerine preparations fixed with Flemming's solution, 

 the external amphids appear as tubular protrusile organs, arcuate in form, and 

 three to four times as long as wide. They may be protruded for at least half 

 their length. Their outer surface is of a refractive character, and there appears 

 to be a slightly refractive core. At the extremity they are almost imperceptibly 

 expanded, somewhat hemispherical in form, with the terminal surface much 

 thinner and less refractive than the lateral. They appear to slide in an inner tube 

 located in the head, which is also cutinized. This tube extends inward and back- 

 ward, and ends opposite the base of the pharynx, and is therefore arcuate like 

 the amphid itself. Tubes leading back from the external amphid may be traced 

 at least half way to the nerve-ring. The inner elements of the tube are refrac- 

 tive, and are seen to lie more or less parallel to the body-axis, but as yet have not 

 been connected up with any internal cellular structure. There are comparatively 

 few ova in the ovary, perhaps about a dozen in all, arranged somewhat irregularly. 

 Habitat: Humus, Plummer's Island, Potomac River, near the District of Colum- 

 bia, U. S. A. Fig. 80, p. 300. 



81. Aphelenchulus mollis n. sp. Cuticle thin, naked; the wings, extending from 

 the neck to near the terminus and bearing about twelve, j- 

 very fine, longitudinal striae, are hardly raised at all. Con- 

 tour, very minutely crenate. The head, which is more or 

 less rounded in the adult, is sub-truncate in the young, and tib (HI- 

 the region is sometimes set off by an almost imperceptible 

 broad, shallow constriction. The spear is nearly vestigial, 

 probably nearly functionless, and may act merely as a tube 

 through which the food passes. It is not clear what the 

 motive force in deglutition is, as the usual oesophageal 

 bulbous pump is absent. Oesophagus cylindroid or faintly 

 cephaloboid. In the larvae opposite the excretory pore are '/'* 

 to be seen two successive breaks in the lining of the oesoph- 

 agus, which are probably vestiges of a bulb. At first, the 

 oesophagus is two-fifths, near the nerve- ring one-half, and 

 finally one-fourth, as wide as the corresponding portion of 

 the neck; the lining is subdistinct, the musculature fine and 

 colorless. There is no car- 1.1 8.9 _u. Y 93.2 x ^ 



dia. The oesophagus ' 9 / 1-8 2-1 

 changes gradually into the 

 intestine, as in Aphelen- 

 chus. In the larvae, the 



.1 / 1.8 2. 2. 2 



Upper Fig Adult male. 



ina 



Lower Figs. Adult female. 



thick-walled intestine gradually becomes three-fifths as wide as the body. 

 Its lining is refractive and in cross-section, it presents one to two cells only, 

 which alternate with each other as in some Rhabdites. The anus is con- 



