NO. 2131. NEMATODE PARASITES OF RODENTS— HALL. 21 



8. Posterior body lengths only slightly smaller than anterior ; spicule 1.7 mm. 



long Trichuris fossor, p. 21. 



Posterior body lengths about half of anterior ; spicule 2 mm. long. 



Trichuris opaca, p. 27. 



The data on described species of Trichuris are so scarce that the 

 above key, based on the limited and little diagnostic features de- 

 scribed, may prove of little value in actual practice. 



TRICHOCEPHALUS CASTORIS Rudolphi, 1819. 



Specific diagnosis. — Trichuris (p. 20) : Characters of the genus. 

 No description. 



Host. — Castor fiber. 



Location. — Large intestine. 



Locality. — Not given. 



Rudolphi (1819) lists this under Species duhiae and states that 

 there is a female specimen in the Vienna Museum. He does not de- 

 scribe it, and von Linstow (1909cj) states that the species is not de- 

 scribed. The name is therefore a nomen nudum, and I have not made 

 the combination with the specific name and the valid generic name 

 Trichuris in order to avoid adding useless synonyms to the literature. 



TRICHURIS CONTORTA (Rudolphi, iSig) Hall, 1916. 



Synonyms. — Trichocephalus contortus Rudolphi, 1819. 



Specific diagnosis. — Trichuris (p. 20) : Characters of the genus, 

 strongly contorted, the considerable folding giving a transient ver- 

 rucous appearance. Ratio of length of anterior esophageal portion 

 of body to length of posterior portion 12 : 10. 



Male 40 mm. long. The flesh-colored body convolute, but not 

 spiral. Posterior portion of body terminates very bluntly. The 

 cloaca is ventral and subterminal. The spicule sheath is short, broad, 

 and truncate. The spicule is narrow and curved. 



Female 50 mm. long. Body contorted, not, as is usually the case, 

 straight or curved. Tail rather pointed. Oviduct black. Eggs 

 elliptical with the usual opercular plugs. 



Hosts. — Georychus capensis {Georhynchus capensis^ Mus capensis, 

 " Georhychos illigeri''''). 



Location. — Cecum. 



Locality. — Cape of Good Hope, Africa. 



TRICHURIS FOSSOR Hall, 1916, new species. 



Synonym. — Trichuris species Hall, 1912. 



Specific diagnosis. — Trichuris (p. 20) : Head conical, about 40 fi 

 in diameter where the sides of the cone tend to flatten into the neck 



