ART. 21 A NEW AMIDOSTOMINE WORM WETZEL 3 



end, are inconspicuous. The excretory pore opens at a distance of 

 about 400jLi to 430/a from the anterior end of the body. 



The head, distinctly set off from the body proper, is about 30/i 

 wide. It shows a special cuticular expansion forming two lateral 

 plates, and one dorsal, and one ventral plate. The lateral plates are 

 not so conspicuous ; both the dorsal and the ventral plate, which have 

 the shape of a spheric triangle, are more prominent. The front sur- 

 face of the head is supplied dorsally as well as ventrally with a pair 

 of flaplike appendices, bending backward in a subdorsal and sub- 

 ventral direction, respectively. Each of these ornaments, corre- 

 sponding to the " deux formations laterales en forme d'epaulettes " 

 of Skrjabin and to the " gros nodules a extremite obtuse, diriges vers 

 I'arriere " of Seurat, terminates posteriorly in a free border with 

 two small incisions, thus forming three small teeth. The lateral 

 papillae or amphids are exceedingly well developed and prominent. 

 On both sides of each lateral amphid there is a glistening spinelike 

 formation, which, as can be seen by a lateral-front-end view, is a 

 kind of support of the outstanding amphid. The four submedian 

 papillae are not so conspicuous; each terminates in two points. The 

 mouth opening is guarded by four toothlike formations arranged in 

 the shape of a rectangle, corresponding to the " 4 papilles avancant 

 en dehors (levres?)" of Skrjabin. The mouth cavity is funnel 

 shaped leading to an elongated club-shaped esophagus. 



Male 6.5 to 7.3 mm. long with a maximum width of 0.150 mm. The 

 esophagus is 0.8 mm. long and surrounded by the nerve ring about 

 260/x posterior to the head. The bursa shows a strong reticulate 

 striation. The well developed lateral lobes are folded ventrally ; the 

 dorsal lobe, while distinct and well set off, is extremely small. It is 

 supported by a short, stout dorsal ray, about 60/i, long, dividing close 

 to the border of the lobe to form four small tips. The externo-dorsal 

 rays are stout, about 1^\i long, terminating with their posteriorly 

 bent, small, hooklike, distal ends some distance from the edge of the 

 bursa. In Skrjabin's Figure No. 13 (p. 478) the distal ends of the 

 externo-dorsal rays are blunt, without the posteriorly bent small 

 hooks; these are also not mentioned by Seurat. The lateral rays 

 have a common stem ; the postero-lateral and the medio-laternls par- 

 allel and terminate in fine points on the bursal margin ; the externo- 

 lateral rays, however, are slightly divergent from the other laterals 

 and have anteriorly bent, hooklike, distal ends, not extending to the 

 border of the bursa. Skrjabin, however, figures (fig. 13, p. 478) the 

 externo-lateral rays as running parallel to the other laterals and 

 their distal ends as extending to near the bursal "margin and having 

 no anteriorly bent hooks, the latter also not being mentioned by 

 Seurat. The ventro-ventral and ventro-lateral rays are slightly di- 



