DIDELTA, DASYNEMA 



253 



markings, reminiscent of the bubbles in defective window glass. The simple, 

 subregular, somewhat asymmetrical, napiform pharynx is about one-third as wide 

 as the head. On the dorsal side of the base of the pharynx there is a more or less 

 glottoid, low, flat elevation, so that the more or less refractive dorsal wall of 

 the pharynx appears only about half as v^ ~Jt f*\ 

 long as the ventral wall. Posteriorly J ^ t /* 

 the neck is cylindroid, anteriorly, more 

 or less conoid. The elliptical amphids 

 are in reality spirals of about one wind. 

 They occur on large, somewhat equilat- 

 erally triangular or deltoid areas on the 

 sides of the head; hence, the name 

 Didelta. The oesophagus is at first 

 about three-fourths, near the nerve- 

 ring one-half, and finally two-thirds, as 

 wide as the corresponding part of the 

 neck. The lining is distinctly indi- 

 cated by a more or less zig-zag, refrac- 

 tive line; the musculature is coarse and 

 colorless. There are no valves, and there is no cardia. The thick-walled intes- 

 tine, which has a distinct refractive lining, becomes at once three-fourths as 

 wide as the body; its cross-section being composed of about six cells. It is sep- 

 arated from the oesophagus by a collum one-third as wide as the base of the neck. 

 The cells of the intestine are packed with more or less uniform granules, having 

 a diameter about one-ninetieth that of the body. Arranged in elliptical clusters, 

 they give rise to a distinct tessellation. The tail, which tapers from the anus, 

 is first conoid, and then more or less cylindroid in the very narrow posterior 

 half. It really tapers throughout, but is nearly cylindroid in the setaceous 

 part. There is no spinneret. The lateral fields are about one-fourth as wide 

 as the body. The nerve-ring is of medium size, and is accompanied by 

 obscure nerve cells. From the rather inconspicuous, but somewhat elevated 

 vulva, the cutinized vagina leads inward two-fifths the distance across the body. 

 The tapering ovaries were not favorable to detailed observation. 



Habitat: "Sea-grass," shoal, two miles off Key West, Florida, U. S. A. Flem- 

 ming to glycerine jelly. Fig. 33. 



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18.4 

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62.5 

 14 



34. Dasynema sexalineatum n. sp. 3 ' 8 ' 3 :7. *i 2.4 Striae resolv- 



able into secondary, elongated elements. Annules retrorse posteriorly, and the 

 reverse anteriorly. Cuticle naked except for the setae on or near the head. 

 yl! Lips three, more or less distinct, thin, apparently 

 acute, possibly conoid, mobile; the appearance is 

 I that of three segments of the head, each armed at 

 the summit with a short, inward-pointing, dark, 

 cutinized apex, having an inward stroke. There 

 does not appear to be a distinct cardia, but a num- 

 , lf , } -~^j,. - / r f small cells forming the beginning of the 

 intestine are manifestly different in structure from 



those directly behind. The rather thin-walled intestine, which has a more or 

 less distinct, refractive lumen, soon becomes two-thirds as wide as the body, 

 and its cross-section is composed of two to four cells in which there are few or 



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