OBSERVATIONS ON THE NEMATODE GENUS NEMATO- 

 DIRUS, WITH DESCRIPTIONS OF NEW SPECIES. 



By Henry G. May/ 



Junior Zoologist, Bureau of Animal Industry, Washington. 



INTRODUCTION. 



There has been in the past some confusion in regard to the identity 

 of the species of Nematodirus. In 1896 Railliet described Strongy- 

 lus spathiger from the camel and distinguished it from Strongylus 

 filicollis (Rudolphi, 1802) from the sheep. Ransom in 1907 pro- 

 posed the genus Nematodirus, with Strongylus flicoUis Rudolphi as 

 type, and in 1911 assigned forms found in the United States in sheep 

 to the species N . fiUcaTlis. His figures of the bursa and spicules of 

 the male agree with the description of N. spathiger, but the female 

 and egg measurements do not agree. In 1912 Railliet and Henry 

 published the following table to distinguish the species of Nemato- 

 dirus and expressed the opinion that the American form described 

 by Ransom as N . -filicollis is N. spathiger. Later authors have been 

 inclined to agree with them. 



Table of Railliet and Henry. 



I Resigned September 2, 1919. 



Proceedings U. S. NAxroNAL Museum, Vol. 58-No. 2350. 

 181404— 21— Proc.N,M.voI.58 37 577 



