256 ORDER ISOLAIMIA 



IV. Order Isolaimia 



37. Rhadinema flexile n. sp. -s/ 1-2 1.5 i-3 ' Cephalic setae 

 3-jointed; cuticle otherwise naked. The thick, small lips confluent. Pharynx 

 exceedingly minute, two-thirds as deep as the head is wide; wall characterized 

 by six longitudinal elements of minute size, exactly parallel to the axis of the 

 head, so that the pharynx appears to be a more or less shallow, cylindroid or 



"Xt Ctth (4) P r i sm id CU P> two-thirds as deep as wide. The lining of 

 the oesophageal canal is more or less modified as far back 

 ^fi/mtphlj) as the base of the amphids. The circumference of the 

 amphids is almost imperceptibly broken on the dorsal 

 The somewhat cylindroid oesophagus is almost 

 imperceptibly swollen in the posterior fifth. At first it 

 is three-fifths, near the nerve-ring one-half, and finally two-thirds, as wide as 

 the corresponding portion of the neck. The lining is subdistinct. There is a 

 more or less hemispherical cardia three-fifths as wide as the base of the neck. 

 The thick-walled intestine, which has a distinct, refractive, more or less zig-zag 

 lumen, becomes at once three-fourths as wide as the body. Its cells are packed 

 with uniform colorless granules of variable size, the largest of which are one- 

 sixteenth as wide as the body. They do not give rise to more than a faint tessel- 

 lation. The tail is conoid. The more or less narrow elongated caudal glands 

 are arranged in a loose tandem behind the anus in the anterior third of the tail. 

 The elongated renette cell lies at a distance behind the base of the neck equal to 

 twice the body-diameter; it is one body-width long, about one-third as wide as 

 long, and contains a rather large nucleus. The rather broad oblique nerve-ring 

 is accompanied by somewhat obscure nerve cells. 



Habitat: Clear, "white" sand, 5 feet of water, cove at the entrance to Buz- 

 zard's Bay, Mass., U. S. A. Sublimate to balsam. Fig. 37. 



4 ?__ __">_} 5. 3'j _ 94. 7_ 



38. Protrellus aureus n. sp. - 7 **/ 3 -_ ' i-' " Annules as much as 

 20 microns wide. Striae are visible throughout the length of young specimens, 

 which also differ from the adults in not having the cuticle inflated on the neck. 

 No setae or amphids. The conoid neck ends in a truncate head, bearing a 

 lip-region set off by constriction, and apparently composed of six lips. There 

 is at least one papilla on each lip. The prismoid pharynx is half as wide as deep. 

 The major part of the oesophagus is simple and cylindrical, having the same 

 width as the lip-region, and is separated from the cardiac bulb by a broad con- 

 striction. The triquetrous lining of the oesophageal tube is easily seen, and 

 ends in a distinct manner near the base of the pharynx. The intestine is modi- 

 fied, i.e., enlarged, to form a sort of "stomach," for a distance equal to twice 

 the width of the body; thereafter its width does not exceed one-fourth that of 

 the body. The length of the rectum is one and one-half times that of the anal 

 body-diameter, and it has the peculiarity of lying close to the ventral side of the 

 body. Region of the ventral excretory pore conspicuously marked by a large 

 colorless ampulla. The lateral fields are one-third as wide as the body. The 

 nerve-ring encircles the oesophagus squarely. The anterior fourth of the tail 

 is somewhat hemispherical, and at the end of this part one-third as wide as at 

 the anus; thence onward it is conical to the acute terminus. The large, ele- 

 vated, and very prominent vulva is situated far forward, somewhat in front of 



