A Nezif Species of Trevmtode 7 



description given is founded on a comparative study of thirteen 

 mounted specimens and one live specimen. 



These worms vary in length from 1.281 mm to 3.5 mm, the 

 mode being 2.013 mm for 14.3 per cent. The width at the 

 widest portion of the body varies between a minimum of 0.256 

 mm and a maximum of 0.458 mm the mode being 0.275 mm 

 for 28.5 per cent. The widest part of the body is in the plane 

 of the ventral sucker 0.591 mm posterior to the anterior end, or 

 approximately at the boundary between the first and second 

 fourths of the length of the body. From this point the outline 

 of the body tapers toward both ends, but much more rapidly 

 toward the posterior than toward the anterior end. The anterior 

 end is, therefore, much more blunt and rounding than the pos- 

 terior, which in some specimens is quite pointed (Plate I, fig. 8). 



The cross-sections vary in form from the anterior end toward 

 the posterior as follows : At the level of the posterior end of the 

 esophagus the worm is very much flattened dorso-ventrally, the 

 form of the section being a long narrow ellipse, and is arched so 

 that the ventral surface is concave from side to side. The dimen- 

 sions are 0.059 mm dorso-ventrally by 0.265 mm wide. From 

 this point caudad to the center of the acetabulum the form changes 

 to a more oval one, and the arch is lost, the ventral surface at 

 this point becoming nearly as convex from side to side as the 

 dorsal surface. Here the body is 0.118 mm dorso-ventrally by 

 0.236 mm wide. From the acetabulum to the ovary it becomes 

 less and less flattened dorso-ventrally until at the ovary the dimen- 

 sions are 0.189 mm by 0.264 mm. From here toward the pos- 

 terior end, the first few sections again resume the long narrow 

 elliptical form but not the arch, then they become very flat on 

 the ventral surface and rounded on the dorsal surface giving 

 somewhat the appearance of a semiellipse with the corners 

 roimded. The dimensions remain very nearly the same as at the 

 level of the posterior end of the esophagus back to the level of 

 the testes. Here the sections become thicker dorso-ventrally but 

 retain their flat ventral surface thus becoming nearly semi-circular 

 in form. The dimensions at the level of the testes are 0.148 mm 

 by 0.254 mm. Posterior to the testes the sections become less 



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