THE NEMATODE FAMILY GNATHOSTOMID.E. 



301 



eacli border. E-ich cervical sac displays a constriction near its 

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

 p. 126) looks upon as a temporary local contraction ; the spicules 

 are stouter than in ^' Cheir acanthus rohustus'' \ the four large 

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

 a considerable interval between Nos. 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 

 Gnathostoma horridum, 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 tm^gida Stossich (1902, p. 13). 



This species is based on a short description of the external 

 characters of two poorly preserve<l females. Stossich is convinced 

 that it is distinct from GnatJiostonia spinigerum, 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 YII., 

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

 of future confusion. Since there is notliing specifically distinctive 

 in the description 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). 

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

 Acuaria pelagica Seurat (1916, p. 785, figs. 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). 



