FREE-LIVING NEMATODES 



4S5 



(12) Pharynx simple, male supplementary organs not in fascicles. 



Doryldimus Dujarciin. 

 Genus consisting, no flouht. of hundreds 

 of species, and inhabiting stjii. frt-sh water, 

 and, to a limited extent, brackish water. 

 They feed so far as known on vcKetahIc 

 matter, most commonly, it is hclieve<l. on 

 the roots of jilants which they pierce by 

 means of the hollow oral sf>car. 



Representative species. 



Dorylaimus Jccuudiis Cobb 1914. 



[-' 



Habitat: 

 ington, D. C. 



Fig. 779. Dorylaimus fecundui. 

 At the right, head and tail of a fi-m.ilc; al the left, 

 tail end of a male, 

 a, apex of spear, showing' ohlique opening: 

 b, papilla of the anterior circlet; c, pantUa of 

 the posterior circlet; d, guidint'-rinR for the 

 spear; e, commencement of the esophaRus, 

 /, pre-rectum; g, rectum; //, anus; i, anai 

 muscles; j, caudal pai)ilhi; k. outer cuticub; 

 /, inner cuticula; m, muscular layer; n, prr- 

 rectum; o, one of the numerous oblicjuc a>|m- 

 latory muscles; P, one of the ventral scries of 

 r, pair of pre-anal papillae; 5, retractor muscles of the 

 accessory piece. (.After Cobb.) 



2 14 I 4 rf^J 4 ' ' — 



Algae, Potomac River, Wash- 



male supplementary organs; q, ejaculatory duct 

 spicula; / 



(11) 



muscular layer; u, right spiculum 



Pharynx with complicated radiate framework, male supplementary 

 organs in fascicles Aclinohiimus Cohh. 



Genus represented in all parts of th world, and proposal for 

 species similar to Dorylaimus labyrinthoslonius, in which the 

 pharynx is more or less immobile, radially striated and elabo- 

 rately constructed. 

 Representative species. 



Actinolaimus nidiatus Cobb 1913. 



The esophagus bcjjins 



e .9 13. 41. -M- ^1 4 I mm "'^ ^ ^"'**^ alx)Ut OnC- 



'' I "8 T. n T. tmI" third as wide as the cor- 



responding portion of the neck. It continues to have this width 

 for some distance. Considerablv in front of the middle of the 

 neck it expands rather suddenly. The cells of the brownish intc-^- 

 tine contain granules of variable size, arranged so as to give n.sc 

 to a rather obscure tessellation. The tail of the female is concave- 

 conoid to the hairfine terminus. The tail of the male is hemi- 

 spherical-conoid. Immediately in front of the anus are two ven- 

 tral papillae placed side by side. In addition t(^ these there are 

 ventral papillae arranged in three raised and conspicuoiis groups 

 or fascicles. These three groups form a .scries whose length is 

 about equal to the distance from the jx.stenor group to the end 

 of the tail. The two equal, slightly arcuate rather aculc 

 spicula are about twice as long as the anal IkkIv diameter The 

 surface of the tail carries a number of innervate<i |upillac. at 

 least as many as six, and probably c|Uite a number of others. 



Habitat: Roots of plants and among algae Potomac River and 

 its banks, Arlington Farm near Wiushington, DC; Douglas 



Lake, Mich. ... ,. , 



Fig. 780. Actttwlamus radiatus 

 lb, lip region; />/>. innervated ixipillae; ph, phao'nx; on. oncho, of 

 spear; or, mouth opening, (.\ller Cobb.) 



13(2) Oral end without protrusile spear or Sting. '-^ 



14 (37) Pharynx armed with one or more refractive, 



Xv5/^ 



cutKular tecti 



