312 BULLETIN 140, UNITED STATES NATIONAL MUSEUM 



A large number of preanal papillae of which one is sometimes median, 

 unpaired, just anterior to the cloacal aperture (the bird forms do 

 not have this papilla present usually; exceptions are Thelazia lutzi 

 and T. campanulata) . Postanal papillae number 3 or 4. Two un- 

 equal spicules. Female with blunt, conical, rounded caudal extrem- 

 ity, provided with 2 lateral papillae. Vulva in anterior part of 

 body, usually slightly posterior to the posterior end of esophagus. 

 Two uteri, directed posteriorly. Embryos hatch in uterus. 



Parasitic normally in the ducts of the lacrimal glands of mam- 

 mals; certain forms occur under the nictitating membrane of the 

 eye in birds. 



Type species. — Thelazia rhodesi (Desmarest, 1828) Blainville, 

 1828, emend. Raillet and Henry, 1910. 



KEY TO SPECIES OF THELAZIA 



1. Description incomplete ; mouth large, the 6 lobes of buccal cavity small, each 



with a finger-like process extending inward ; from Crax fasciolata. 



Thelazia anolabiata, p. 317. 



Mouth and lobes of buccal cavity not described as above; from hosts other 



than above 2. 



2. Male 22 to 24 mm. long ; female 25 to 27 mm. long ; 10 pairs of preanal papil- 



lae; cloacal aperture 85m from posterior end Thelazia lutzi, p. 315. 



Male smaller than above (up to 20 mm. in T. papulosa) ; female smaller 

 than above except in T. papulosa (up to 26 mm.) ; in T. papulosa, as 

 in all other species where number is given, less than 10 pairs of preanal 

 papillae ; cloacal aperture, if described, less than 85m from posterior 

 end 3. 



3. No cuticular annulations ; no buccal cavity ; no caudal papillae in male. 



Position in this genus doubtful Thelazia cirrura, p. 318. 



Cuticular annulations, buccal cavity, and caudal papillae present 4. 



4. Cervical region with rows of delicate posteriorly directed spines ; left 



spicule 6 times as long as right spicule Thelazia papillosa, p. 317. 



Cervical region without spines ; left spicule, if lengths given, more than 

 6 times as long as right spicule 5. 



5. Esophagus not over 600/* long ; anus of female 300m or farther from pos- 



terior end 6. 



Esophagus 750m long or longer; anus of female not over 225m from posterior 

 end 7. 



6. Maximum length of esophagus 340m ; vulva 680m from anterior extremity. 



Thelazia stereura, p. 316. 

 Length of esophagus 460 to 600m ; vulva not over 500m from anterior extremity. 



Thelazia campanulata, p. 313. 



7. Female with buccal cavity 33m deep ; esophagus 925m long ; anus 85m from 



posterior end Thelazia cholodkowskii, p. 313. 



Female with buccal cavity not over 28m deep ; esophagus not over 850m 

 long; anus 120m or farther from posterior end '. 8. 



8. Female 18 mm. long; anus 120m from tail end Thelazia digitata, p. 319. 



Female not over 14 mm. long ; anus 255m from tail end. 



Thelazia dacelonis, p. 314. 



