364 BULLETIN 140, UNITED STATES NATIONAL MUSEUM 



teriorly directed, giving off 2 to 4 uterine branches. Eggs with thin 

 shells, ornamented externally with fine granulations. 



Parasitic, usually in the digestive tract, of reptiles, fish, mammals; 

 rarely, as larvae, encysted in birds. 



Type-genus. — Gnathostoma Owen, 1836. 



Subfamily Gnathostominae Baylis and Lane, 1920 



Sub family diagnosis. — Gnathostomidae (p. 363) : A cuticular head 

 bulb present, provided with transverse striations or rows of hooks, 

 and containing 4 (or 6?) membranous ballonets, the cavity of each 

 communicating with an elongated, blind, cervical sac hanging freely 

 in body cavity and functioning as glandular apparatus. 



Type-genus. — Gnathostoma Owen, 1836. 



Genus GNATHOSTOMA Owen, 1836 



Synonym. — G heir acanthus Piesing, 1838. 



Generic diagnosis. — Gnathostominae (p. 364) : Head-bulb armed 

 with simple hooks. Anterior part or entire body covered with spines, 

 the anterior spines incised into points of varying number and shape. 

 Male with unequal spicules; 4 pairs of large lateral and 2 pairs of 

 small ventral caudal papillae. Female with vulva posterior to mid- 

 dle of body. 



Parasitic normally in gastric wall, usually of carnivorous mam- 

 mals; occasionally as larvae in subcutaneous tissue of birds. 



Type-species. — Gnathostoma spinigerum Owen, 1836. 



KEY TO SPECIES OF GNATHOSTOMA 



Glandular apparatus of head consisting of 6 tubes; length of esophagus equal 

 to almost 1/2 that of body ; as encysted larvae and immature adults in 

 Pelecanus onocrotalus Gnathostoma pelecani, p. 365. 



Glandular apparatus of head consisting of 4 tubes ; length of esophagus equal 

 to 1/3 that of body ; as encysted larvae in Aquila impenalis. 



Gnathostoma accipitri, p. 364. 



GNATHOSTOMA ACCIPITRI Skrjabin, 1916b 



Host. — Aquila imperialis. The parasite is probably aberrant so 

 that this does not represent either primary or secondary host. 



Location. — Encysted in subcutaneous connective tissue. 



Morphology. — Gnathostoma (p. 364) : Larval form. Body curled 

 in circle in nodule; body length 2.8 mm., width 510/x. Head (fig. 

 425a) set off from body by depression and encircled by 4 parallel 

 transverse rows of chitinous hooks or spines (fig. 425 b), 44 spines 

 in each circle. Head 150> long by 340/* wide. Two valve-like lips, 

 each with a strongly-developed papilla. Cuticle of body covered 



