232 FILARIOIDEA 



accessory piece present. Four pairs of preanal and six pairs 

 of postanal papillae present. Vulva in middle region of body. 

 Uterine branches opposed. Eggs contain embryos when laid. 



Hab. Intestine of a Rodent (one species known). 

 Genotype : ^S'. [Ophiostomum] tacapense (Seurat, 1915). 



Seurat, 1915, Compt. rend. Soc. Biol., Paris, Ixxviii, 20; 

 Hall, 1916, Proc. U.S. Nat. Mus., 1, 62; Baylis, 1923, Para- 

 sifol., XV, 32. 



Hall (1916) has suggested a subfamily Seuratinae for the 

 reception of Seuratum. He considers that this subfamily 

 should be included in the Heterakidae, although admitting 

 that the affinities of the genus are perhaps closer with 

 Dacnitis, now recognised as a synonym of Cucullanus. It 

 differs from Cucullanus in the absence of a sucker-like organ 

 in the male, and in the absence of a marked dilatation of the 

 anterior end of the oesophagus. It is, however, insufficiently 

 described. 



Fam. 6. GNATHOSTOMIDAE RaiUiet, 1895. 



Lips large, trilobed, having the cuticle of their imier surfaces 

 thickened and usually raised into longitudinal tooth-like 

 ridges which meet or interlock. Vagina runs forward from 

 vulva. Two or four uterine branches. Eggs with thin shells, 

 ornamented with fine granulations. 



Subfam. 1. GNATHOSTOMINAE Baylis & Lane, 1920. 



Lips followed by a cuticular head-bulb provided either with 

 marked transverse sti'iations or with rows of backwardly- 

 directed hooks, and containing four membranous submedian 

 " ballonets," the cavity of each of which is in communication 

 with one of four elongated, blind cervical sacs. 



1. Gnathostoma Owen, 1836. 



Syn. Cheiracanthus Diesing, 1838. 



Head-bulb armed with simple hooks, and showing no 

 external evidence of the presence of the "ballonets." No 

 cuticular collar behind the head-bulb. Body with cuticular 

 spines, anteriorly scale-like, with their free edges dentate, 

 and posteriorly becoming less subdivided until finally they 

 appear as simple spines or disappear altogether. Tail of 

 male with four pairs of large lateral and two pairs of small 

 ventral papillae. Spicules unequal. Vulva behind middle 

 of body. Two uterine branches. 



Hab. Gastric wall of Mammals (usualty of Carnivores). 

 Genotype : G. spinigemm Owen, 1836. 



