18 PROCEEDINGS OF THE NATIONAL MUSEUM vol.75 



KEY TO SPECIES OF OKNITHOBILHARZIA ^ 



1. Parasitic in mammals 2. 



Parasitic in birds 3. 



2. Cuticle of male smooth ; testes 70 to 80 in number ; egg 72^ to 74^ by 22^ to 



26fi, with a spinous process at each pole 0. turkestanicum, p. 21. 



Cuticle of male tuberculate; testes 61 in number; egg 100^4 to 13Gm by 44^1 to 

 60/x, with a spine at one pole 0. bomfordl, p. 22. 



3. Species inadequately described 4. 



Species adequately described 5. 



4. Male 14 mm. long ; oral sucker 364,it in diameter ; acetabulum 560ai in diam- 



eter ; female unknown ; in Hydrocoloeus melanocephalus. 



0. kowalewskil, p. 19. 



Male 16 mm. long ; oral sucker S12fi by 104/ii to 160(U ; acetabulum 450m in 



diameter; female shorter than male; in Thalasseiis maximus (=Sternn 



r/alcriculata) 0. canaliculata, p. 19. 



5. Male 40 to 57 mm. long ; testes 230 to 250 in number ; female unknown. 



0. macrobilharzia, p. 21. 

 Male 11 mm. or less in length; female known 6. 



6. Male 8 to 10.6 mm. long ; testes 90 to 110 in number ; intestinal ceca in femsle 



unite posteriorly immediately caudad of ovary 0. intermedia, p. IS. 



Male 6 to 7 m. long ; testes 65 in number ; intestinal ceca unite posteriorly a 

 considerable distance caudad of ovary 0. odhneri, p. 20. 



OKNITHOBILHARZIA INTERMEDIA Odhner. 1912 



Figure 39 



Specific diagnosis. — Ornithobilharzia : 



Male 8 to 10.6 mm. long and 420/a wide. Cuticle jDrovided with thick 

 blunt spines. Oral sucker 200/j, to 250yu, in diameter ; acetabulum SOO^u, 

 to 350/i in diameter. Testes 90 to 110 in number, commencing a 

 short distance caudad of acetabulum and extending almost to posterior 

 fourth of body; terminal portion of genital system (Endapparat) 

 small and situated at posterior edge of acetabulum; seminal vesicle 

 entirely outside of a rudimentary cirrus pouch ; prostate absent. The 

 genital pore is situated immediately caudad of the acetabulum and 

 to the left of the median line. 



Femcde 4.5 to 5.75 mm. long and ITO/a to 220/a Avide in region of 

 ovary. Cuticle spin3^ Oral sucker 40/x to 50/>i in diameter; acetabu- 

 lum 25/A to 35/A in diameter. Ovary long, spirally twisted, and situ- 



* While this paper was in preparation, Linton (1928) described an Omitliobilharzia spe- 

 cies from several water birds at Woods Hole, Mass. The writer has recently examined 

 specimens of this species which were deposited in tlie U. S. National Museum, and also 

 several additional specimens which Trofessor Linton kindly loaned for study. In this 

 material there appear to be two species represented. The specimen (Cat. No. 7946, 

 U. S. N. M.) from Larits argvntatus is a species of OrnithobiUiarzia, but owing to the 

 fact that the female is inclosed in the gynaecophoric canal of the male, it is impossible 

 to make out the necessary specific characters. The remaining specimens, with the pos- 

 sible exception of the one from Nycticorax nycticorajc naevius (which is in such a poor 

 state of pre.servation that none of the structures c:ui be made out) appear to be closely 

 related to, if not identical with, Microhilharzia chaplni. The males of these specimens are 

 somewhat more robust than M. chapini from Marila affinis, but are otherwise very similar. 



