CYNURA, XINEMA 



263 



Habitat: Seaweed, washed up at Ocean Beach, Miami, Fla., U. S. A., after a 

 storm. Flemming to glycerine jelly. Only a single specimen seen. Fig. 46, p. 262. 



47. Xinema perfectum n. sp. Neck conoid. Somatic setae papilloid, or nearly 

 so; cuticle becoming much thinner in the region of the lateral organs, thickening 

 again in front of them and becoming again as thick as ever on the front of the 

 head. The oesophagus continues to have the same diameter until after it passes 

 through the nerve-ring, when it begins to expand gradually, until finally it is 

 nearly three-fourths as wide as the base of the neck. The two ventrally sub- 

 median sectors of the oesophagus appear to contain glands, at least in each there 

 extends from near the posterior end of the oesophagus forward a minute duct, 

 which stains distinctly with carmine. This duct can be traced at least as far 

 as the nerve- .4 .4.5 : 8.7 "-&-" 94.3 y23 



ring. There does """>''""" .s Of* ' 



not appear to be .3 4.4. s.s> -M-" 94. ^ 24 



any very distinct W*"xi/":i i'.ir^U 



cardia. The intestine gradually becomes three- 

 fourths as wide as the body. In cross-section 

 it is composed of six to eight cells, containing 

 relatively large nuclei and numerous small, uni- 

 form granules. The renette cell, nearly as long 

 as the body is wide and about one-third as wide #" 

 as long, is located just behind the base of the neck. Its ampulla, about one- 

 fourth as wide as the corresponding portion of the neck, is connected with the 

 excretory pore by means of a very short duct. The lateral fields are about one- 

 third as wide as the body. The nerve-ring surrounds the oesophagus squarely. 

 The tail tapers from considerably in front of the anus, being convex-conoid in 

 such a fashion that at the beginning of the final fifth it has a diameter about 

 one-fifth as great as at the anus, or even less; thence onward, the tail expands 

 a little. The caudal glands are located near the anus. From the depressed 

 vulva, the vagina leads inward more than half way across the body, where it 

 joins the two symmetrically-placed uteri; its internal walls are distinctly cutin- 

 ized. The ovaries contain twelve to fifteen ova arranged single file. Occasion- 

 ally the tips of the ovaries are reflexed. Apparently the females possess a pair of 

 spermatheca, which when filled reach to near the bases of the ovaries. The sper- 

 matozoa appear to be elongated. The elongated eggs are about twice as long 

 as the body is wide and a little less than half as wide as long; they have been 

 seen in the uteri one at a time. Tail of the male a little more bulky than that of 

 the female and a little narrower in the posterior part, which instead of constitut- 

 ing one-fourth of the tail, constitutes about one-third. No supplements or 

 special setae. Spicula consisting of two, equal segments, one in front of the 

 other. The muscular tunic enclosing the spicula is continuous at the elbow. 

 While the spicula and their sheaths tend to stain in acid carmine, the accessory 

 pieces do not do so, but retain a slight yellowish color of their own. The caudal 

 glands are located alongside the accessory pieces, both in front of the anus and 

 behind it. The ejaculatory duct is about one-fourth as wide as the body, the 

 vas deferens about one-third. 



Habitat: Marine mud, San Pedro, California, U. S. A. Specimens of this 

 species appear to have a tendency, when killed with hot sublimate, to twist and 

 present a dorsoventral view of the head instead of a lateral. Fig. 47. 



