66 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 50. 



The genus Oxyuris includes about 100 species, but a study of over 

 a dozen species shows the general characteristics quite constant and 

 the variable features not readily capable of a group arrangement. 



ANALYTICAL KEY TO SPECIES OF OXYUKIS. 



Females. 



1. Description inadequate; in Procavia syriaca (Hyrax syriarus). 



Oxyuris pnyio, p. 83. 

 Description recognizable 2. 



2. Vagina normally everted externally through vulva 15. 



Vagina not normally prolapsed 3. 



3. Over 2 cm. long, the tail approximately equal to the rest of body. 



Oxyuris ohesa, p. 80. 



Less than 2 cm. long, or if more, tail not approximately equal to rest of 



body 4. 



4. Mouth with six hooklike lips bent outward Oxyuris hamata, p. 79. 



Mouth not provided with hooklike lips 5. 



5. Tail ornamented with 35 to 48 prominent cuticular annuli. 



Oxyuris ambigua, p. GS. 

 Tail not ornamented with cuticular annuli 6. 



6. Head strongly inflated ; cervical alae terminate posteriorly in recurved 



margins Oxyuris tetraptera, p. 86. 



Head not strongly inflated 7. 



7. Posterior half of esophagus conspicuously pigmented brown, 



Oxyuris polyoon, p. 98. 

 Posterior half of esophagus not differentially pigmented 8. 



8. Over 20 mm. long Oxyuris flagellum, p. 77. 



Less than 20 mm. long 9. 



9. Over 15 mm. long Oxyuris sciuri, p. 84. 



Less than 15 mm. long 10. 



10. Over 10 ram. long Oxyuris stossicM, p. 8i. 



Less than 10 nun. long 11. 



11. Over 8 mm. long Oxyuris acutissima, p. 67. 



Less than 8 mm. long 12. 



12. Cervical alae present Oxyuris ungula, p. 94. 



Cervical alae absent or inconsi)i('uous 13. 



13. Mouth with four double and two single papillae Oxyuris stroma, p. 85. 



Mouth with single papillae 14. 



14. Vulva transversely elongate and followed posteriorly by bulla. 



Oxyuris triradiata, p. 90. 

 Vulva on a more or less prominent cone, not followed by bulla. 



Oxyuris ohvelata, p. 81. 



15. Not over 3 nun. long; lateral alae in median region of body. 



Oxyuris pallaryi, p. 95. 

 More than 5 mm. long; no lateral alae in median region of body 16. 



16. Maximum length 18 mm Oxyuris evoluta, p. 70. 



Maximum length 12.7 mm Oxyuris hilgerii,p.74:. 



Males. 



1. Males unknown Oxyuris acutissima (p. 67), 0. flagellum (p. 77), O. hamata 



(p. 79), O. obesa (p. 80), O. sciuri (p. 84), O. pugio (p. 83). 

 Males known 2. 



