Fig. 143. — Nematodirus filicollis; male in center, female at left. * Vulva. xl5. At 

 right, enlarged anterior portion of body. (After Ransom, Bull. No. 127, Bureau An. Ind., 

 U. S. Dept. Agr.). 



Fig. 144. — Cooperia oncophora; male at right, female 

 at left. * Vulva. xl5. (After Ransom, Bull. No. 127, 

 Bureau An. Ind., U. S. Dept. Agr.). 



