ATRACTIDAE 33 



Tail of male tapering, without alae. Reproductive organs 

 simple. Spicules two. Vulva close to anus, exceptionally 

 with a common opening. Female genital tube single. Eggs 

 few, very large. Viviparous. 



Hab. Alimentary canal of Vertebrates. 



1. Atractis Dujardin, 1845. 



Lips not distinct, apparently six. Neck of oesophageal 

 bulb narrower than the oesophagus proper. Tail of male 

 constricted behind the anus to form a conical process. Nine 

 pairs of caudal papillae present, of which six pairs are postanal. 

 Spicules unequal and markedly dissimilar. In addition to 

 these there is a tubular chitinoid accessory organ. Tail of 

 female conical. 



Hab. Alimentary canal of Tortoises and Iguanas. 

 Genotype : A. [Ascaris] dactyluris (Rudolphi, 1819). 



Rudolphi, 1819, Entozoorum Synopsis, 40, 272 ; Schneider, 

 1866, Monograjjhie der Nematoden, Berlin, 124; Drasche, 

 1884, Verhandl. k. k. Zool.-bot. Ges., Wien, xxxiii; 328, Parona, 

 1887, Ann. Mus. Civ. Stor. Nat., Genova, xxiv, 344; v. Lin- 

 stow, 1883, Arch. f. Naturg., xlix, 296; Gedoelst, 1919, 

 Compt. rend. Soc. Biol., Paris, Ixxxii, 910. 



2. Labiduris Schneider, 1866. 



Three large and distinct lips, the dorsal lip smaller than the 

 two ventro-lateral and trilobed anteriorly, each ventro- 

 lateral lip with a conical process in front and a fringe of 

 knobbed bristles behind. Tail of male sharply constricted 

 behind the cloaca to form a long, slender terminal process. 

 Ten to twelve pairs of caudal papillae present, of which four 

 or five sessile pairs are preanal. The two most anterior 

 pairs of postanal papillae very large and prominent, the most 

 posterior pair supporting the posterior angles of smaU square 

 alae. Spicules equal. Accessory piece absent. Tail of 

 female long and pointed. 



Hab. Large intestine of Tortoises. 



Genot3rpe : L. [Ascaris] gulosa (Rudolphi, 1819). 



Rudolphi, 1819, Entozoorum Synopsis, 40, 271 ; Schneider, 

 1866, Monographie der Nernatoden, Berlin, 122 ; v. Linstow, 

 1899, Mitt. Zool. Mus., BerHn, i, 13 ; Gedoelst, 1919, Compt. 

 rend. Soc. Biol., Abt. A, Paris, Ixxxii, 912. 



3. Crossocephalus Railhet, 1909. 

 Syn. Pterocephalus v. Linstow, 1899, nee Schneider, 1887. 

 Three distinct lips, each bearing two chitinoid jaws with a 

 terminal tooth and a row of bristles externally. The jaws 



SYN. NEM. D 



