NO. 2131. NEMATODE PARASITES OF RODENTS— HALL. 67 



2. Not over 2 mm. long; tail with preanal bulla and 3 large preanal cuticular 



bolster.^ Oxyurls stroma, p. 85. 



Not over 2 nun. long and with only 2 preanal cuticular bos.ses ; or more than 

 2 mm. long and no preanal bulhi or bolsters present 3. 



3. Not over 2 mm. long and with 2 preanal cuticular bosses. 



Oxyuris paUaryi, p. 95. 

 More than 2 nun. long and no preanal bosses present 4. 



4. Tail hoof-shaped in lateral view and with two cuticular projections on each 



side Oxyuris nnyula, p. 94. 



Tail not hoof-shaped 5. 



5. Prominent bursa supported by a large dorsal and 2 large lateral rays. 



Oxyuris triradi'ita, p. 90. 

 No such bursa formation 6. 



6. Posterior half of esophagus conspicuously pigmented brown. 



Oxyuris polyuou, p. 98. 

 Posterior half of esophagus not differentially pigmented 7. 



7. No lateral alae other than small cuticular ridges on each side of lateral 



lines Oxyuris ambiyua, p. 68. 



Lateral alae present in cervical region 8. 



8. Prominent conical raylike postanal papillae Oxyuris c r olut a, i>. 70. 



Postanal papillae not raylike 9. 



9. From 5 to 8 mm. long Oxyuris sfossiclii, y>. S-i. 



Not over 6.2 mm. long 10. 



10. From 3.8 to 6.2 mm. long Oxyuris hilycrti,i).7-i. 



Not over 3 mm. long 11. 



11. Head strongly inflated ; cervical alae terminating posteriorly in recurved 



margins Oxyuris tctraptcra, p. 86. 



12. Head not strongly inflated; no cervical alae present Oxyuris obvcUitn, p. 81. 



OXYURIS ACUTISSIMA (Zeder. i8oo) Hall, 1916. 



Synonyms. — Fusaria acutlss'tma Zeder, 1800; Asca7'ls acutlssmia 

 (Zeder, 1800) Rudolphi, 1809. 



Specific diagnosis. — Oxyuris (p. C5) : Body thinned at both ends, 

 the anterior end thicker. Head pointed, with three hps. Two 

 lateral alae extending to the caudal extremity. Esophagus at first 

 narrow, then considerably dilated, and separated by a constriction 

 from the much dilated origin of the intestine. 



Male unknown. 



Female 8.4 mm. long. Tail almost trihedral, subulate, diaphanous, 

 and comprising almost a third of the entire length of the worm. 

 The vulva has prominent lips and is situated at the thickest part of 

 the body. 



Host. — Sciurus vuhjaivs. 



Location. — Cecum. 



Locality. — Vienna, Austria. 



Dujardin (1845) states that he has not been able to find this 

 parasite, but from the description of Zeder, the only one who has 

 seen the worm, he judges it be an Oxyuris. There appears to be 

 little question but that this should be transferred to the genus 

 Oxyuris, 



