248 ORDER CiTTOLAIMIA 



has been impossible to determine with exactitude the entire course of the ducts 

 of these various glands, but most of them have been seen to be connected with 

 the rectum, and all are believed to be so connected, though it is possible that 

 some of them may deliver into a common duct before reaching the rectum. As 

 to the structure of these glands, the description of one of them will answer fairly 

 well for all the others. In the fixed specimens, the anterior extremity of each 

 contains a spherical nucleus with a strongly staining nucleolus : the nucleus lies 

 in the midst of chromatin matter which stains rather strongly with acid carmine. 

 The nucleus and chromatin occupy the anterior fourth, or third, of the glandu- 

 lar cell. The remainder of the contents is of a uniformly fine, granular nature. 

 This granulation is also characteristic of all the ducts. 



Habitat: Punta Arenas, Pacific Coast of Costa Rica. Diatomivorous. Sub- 

 limate to balsam. Fig. 26, p. 247. 



27. Margonema ringens n. sp. Striae unaltered on the lateral fields. Cuticle 

 apparently naked, but it is possible that through rough handling cephalic setae 

 fp/Jb may have been broken off, as was the case with some other 

 , specimens in the same collection. Lips three and double. 

 Neck cylindroid. Amphids faint. Oesophagus at first two- 

 subait thirds, near the nerve-ring one-half, and finally two-thirds, 

 _^ as wide as the corresponding portion of the neck; its lining 

 indistinct. There is a faint, rather flat cardia about half as 

 aw son wide as the base of the neck. The cross-section of the thick- 

 setsm walled intestine is made up of two cells. These transparent, 

 elongated cells have very distinct nuclei, but few and small 

 X75 inconspicuous granules. The intestine becomes at once two- 

 "-6Q- ' 9*- 2 * t 7 thirds as wide as the body, and is separated from 

 .9 / 1.2 1.2 1.5 i- 2 the oesophagus by a collum two-thirds as wide as 



the base of the neck, and has a faint zig-zag lumen. 



k. p 12: 'fl ^-^> 1.5. .From the anus, the posterior lip of which is ele- 

 vated, the prominent rectum extends a distance 



about as long as the anal body-diameter. The conoid tail tapers from the anus. 

 The three ellipsoidal caudal glands lie in a loose tandem in the anterior two- 

 fifths of the tail. There are no caudal setae. The lateral fields are about 

 one-third as wide as the body, and contain both small and large nuclei. At a 

 distance behind the neck equal to twice the width of the body lies the ellip- 

 soidal renette cell, which is about as long as the body is wide and about half 

 as wide as long, It empties through an ampulla about as long as the neck is 

 wide, and about one-fourth as wide as long. This latter is connected with the 

 excretory pore by a very short duct. The nerve-ring surrounds the oesoph- 

 agus squarely, and is accompanied by distinct cells apparently not very defi- 

 nitely arranged. From the somewhat depressed, more or less continuous vulva, 

 the tubular vagina extends nearly half way across the body. The vagina is 

 bifurcated, each branch being about half as long as the body is wide. The 

 uteri are narrow. The eggs are three-fifths as wide as the body, and six times 

 as long as the body is wide. The narrow ovaries taper but little, and contain 

 about a dozen ova approximately in single file. At their widest part, the slen- 

 der, acute spicula are about one-eighth as wide as the corresponding portion of 

 the body. Their arcuate, cephalic portions, viewed in profile, appear to lie 

 somewhat ventrad from the body-axis. The subarcuate, rather slender, frail, 

 simple accessory pieces are joined together at the anus. The separate apophysis 



