20 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 50. 



Genus TRICHURIS Roederer, 1761. 



Synonyms. — Trichocephalos Goeze, 1782 ; Trichocephalus Schrank, 

 1788; Mastigodes Zeder, 1800; Trlcocefhalos Lamarck, 1801; Tri- 

 churis Eoederer and Wagler, 1761, of Stiles and Hassall, 1905. 



GeTieHc diagnosis. — Trichiirinae (p. 19) : Anterior esophageal por- 

 tion of body very slender and longer than the posterior portion, 

 which is much thicker and contains the reproductive organs. Poste- 

 rior extremity of body blunt and rounded. Anus terminal or sub- 

 terminal. On the ventral surface of the anterior esophageal portion 

 of the body is a longitudinal bacillary band, terminating near the 

 union of the anterior and posterior portions of the body, and formed 

 of punctiform projections which are the ends of small rodlike struc- 

 tures originating in subcuticular cells and penetrating the cuticle. 

 The cuticle has transverse striations forming annuli, which have the 

 posterior edges projecting slightly in such a way as to give the body a 

 finely serrate appearance in profile. This striation is absent from the 

 ventral surface covered by the bacillary band. 



Male. — Posterior portion of body rolled dorsally in a spiral. Spic- 

 ule surrounded by a prepucelike sheath, which evaginates when the 

 spicule is protruded. The sheath is a soft structure of variable shape 

 and size. External surface of the evaginated sheath smooth or cov- 

 ered with spines. 



Female. — Posterior portion of body may be slightly curA'ed, but 

 not rolled into a spiral. Vulva near the union of the anterior slender 

 portion and the posterior thick portion of the body. Eggshell thick, 

 usually brown, and with the opening at each end of the shell closed 

 with an opercular plug, giving the Qgg the characteristic lemon shape. 



Type-species. — TrichuHs trlcMura (Linnaeus, 1767) Stiles, 1901. 



ANALYTICAL KEY TO SPECIES OF TRICHURIS. 



1. No description whatever Trichocephalus castoris, p. 21. 



Described species 2. 



2. Anterior and posterior portions of body of almost equal length. 



Trichuris gracilis, p. 23. 

 Anterior portion of body longer than posterior 3. 



3. Ratio of length of anterior portion of body to length of posterior portion 2 : 1 



or 3: 1, minimum length around 50 mm Trichuris oris, p. 28. 



Ratios smaller than the above, or minimum length less 4. 



4. Female contorted, not straight or curved Trichuris contorta, p. 21. 



Female straight or curved, not contorted 5. 



5. Maximum length of spicule 7 mm Trichuris leporis, p. 24. 



Maximum length of spicule not over 2 mm 6. 



6. Worms 44.6 to 52.1 mm. long Trichuris infundibulus, p. 23. 



AVorms not over 35 nun. long 7. 



7. Spicule less than 1 nun. long ; ratio of anterior to posterior body lengths 5 : 3 



in male and 7 : 4 in female Trichuris muris, p. 26. 



Spicule more than 1 mm. long 8. 



