136 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 50. 



Fig. 172.— Ne- 

 matodirus 



NEOTOMA. 



Anterior 

 extremity 

 of female. 



X 170. 



NEMATODIRUS NEOTOMA Hall, 1916, new species. 



Synonym. — Nematodirus species Hall, 1912. 



Specific diagnosis. — Nematodirus (p. 131) : Long and slender, nar- 

 rowing toward the anterior end. Head diameter, exclusive of the 



inflated cuticle, 25 to 45 /x; inclusive of the inflated cuticle, attains a 

 maximum of 80 /x. The cuticle of the head and neck is 

 usually inflated and, as a rule, asymmetrically (fig. 172). 

 The inflated area shows a transverse striation. The re- 

 mainder of the body is finely striated longitudinally, the 

 striae being 10 to 11 /x apart, and the striation is continued 

 along the rays of the bursa. A yet finer transverse stria- 

 tion is visible over the body in favorable specimens, and a 

 special transverse striation forms a fine annulation in the 

 region of the vulva and ovijectors. Four circumoral 

 papillae visible. The anterior portion of the esophagus 

 usually has a sinuous course and is narrower than the 

 straight posterior portion. 



Male 8.1 to 10.6 mm. long with a maximum thickness of 

 135 /i. Esophagus 335 to 500 /x long. The dorsal lobe of 



the bursa (fig. 173) has a shallow median notch along its border, the 



two lobules thus formed being supported by the two dorsal rays. 



These rays bifurcate near their tips, the bifurcated part being about 



one-fifth of the total length of the ray. The externo- dorsal rays are 



very long and slender and 



have a rather sinuous course 



in most specimens (fig. 174). 



They are remote from the 



other rays. The postero-lat- 



eral and medio-lateral rays 



are parallel branches formed 



by a split in their common 



stem (fig. 175). Their tips 



curve back toAvard the ex- 



terno-dorsal ray. P>om the 



same common stem the ex- 



terno-lateral ray diverges, its 



tip turning toward the ventral 



rays which are parallel and 



close together. Around the 



proximal part of the lateral 



ray and in the area between the externo-lateral and the other lateral 



rays are a number of clear, transparent maculae. The body terminates 



in a cone inside the bursa (fig. 176) . The spicules are very long, from 



3 to 3.42 mm. long, and are only clearly separated for a short distance 



Fig. 173.— Nematodirus neotoma 

 VIEW. X 170. 



Bursa, dorsal 



