THE NEMATODE FAMILY GNATHOSTOMID/E. 301 



each border. Each cervical sac displays a constriction near its 

 posterior end, a condition, however, which v. Drasche (1882, 

 p. 1 26) looks npon as a temporary local contraction ; the spicules 

 are stouter than in '■'■ Cheiracanthits rohitstus"; the four large 

 lateral caudal papillae of the male are so arranged that there is 

 a considerable interval between IS^os. 1 and 2 ; the egg is figured 

 as being without a polar cap, and the habitat was the intestinal 

 canal of a fish which reaches a length of 15 feet and is presumably 

 carnivorous. 



The great length and unusual habitat suggest, as in the case of 

 Gnathostomahorridani, that the real host was some mammal which 

 was devoured by the " Pirarucu." 



Specific Diagnosis. 



Gnathostoma gracile (Dies., 1838). 



Gnathostoma : anterior body-spines leaf -like, with five points, 

 one at the tip and two along each edge. 



5. Gnathostoma turgidum Stossich, 1902. 



Gnathostoma turgicla Stossich (1902, p. 13). 



This species is based on a short description of the external 

 characters of two poorly preserved females. Stossich is convinced 

 that it is distinct from Gnathostoma S'pinigerum, basing his con- 

 viction on the statement that the discoidal head-bulb has from 

 10 to 12 rows of spines, the body is cylindrical and tapers in 

 both directions, and its spines are of varying shape. There is no 

 further information beyond the details to be found in Table VII., 

 p. 302, and Table VIII. , p. 304. The name is likely to be a source 

 of future confusion. Since there is nothing specifically distinctive 

 in the descrijotion no specific diagnosis is possible. 



Species which have been attributed to the G-enus Gnathostoma. 



Gnathostoma shipleyi Stossich, 1900. 



Gnathostoma shipleyi Stossich, in Shipley (1900, p, 560, fig. G). 

 liictularia 'paradoxa v. Linstow (1903, p. 272 ; pi. xviii. fig. 5). 

 Acuaria pelagica Seurat (1916, p. 785, ligs. 1-5). 

 Seuratia shipleyi Skrjabin (1916, p. 971). 



Seurat's careful description of the female of this species dis- 

 closes neither cervical sacs nor ballonets. The absence of these 

 and of trilobed lips excludes the worm from the Gnathostomidse. 



Gnathostoma pelecani (Chatin, 1874). 



Sclerostoma pelecani Chatin (1874, p. 6 ; pi. viii. fig. 12 ; pi. ix. 

 figs. 1, 2). 



Gnathostoma pelecani Skrjabin (1916, p. 972). 



