ONCHOLAIMmAE 111 



Pharynx spacious, cylindrical or six-sided, containing a dorsal 

 and two subventral teeth. One of the subventral teeth is 

 larger than the others, and all the teeth carry the ducts of 

 oesophageal glands. Oesophagus gradually swollen behind, 

 without bulb. Ocelli sometimes present. A single accessory 

 piece may be present. Testis single or paired. Female 

 genital tubes paired, opposed, or single, anterior, always 

 reflexed. A peculiar " tubiform organ " in the body-cavity 

 of the female, opening by paired lateral pores near the anus. 

 Caudal glands present. Specialized spinneret apparently 

 absent. 



Hab. Mostly marine, a few species in fresh or brackish 

 water. 



Genotype : Probably O. attenuatus Dujardin, 1845, accord- 

 ing to Stiles and Hassall (1905). 



Dujardin, 1845, Histoire naturelle des Helminthes, Paris, 

 230, 235; de Man, 1884, Die frei . . . lebenden Nematoden 

 der Niederl. Fauna, 67; Cobb, 1918, in Ward & Whipple, 

 Freshwater Biology, 487 ; Micoletzky, 1922, Arch. f. Naturg., 

 Abt. A, Ixxxvii, 331 ; Filipjev, 1918, Trav. Lab. Zool., Stat. 

 Biol. Sebastopol, Ser. II, No. 4, 110 ; 1924, Zool. Anz., Iviii, 108. 



Viscosia is regarded by some authors (Micoletzky, 1922) 



as a subgenus of Oncholaimus. Its chief peculiarity appears 



to be the viscous nature of its cuticle, and this scarcely seems 



to warrant its separation from tjrpical forms. Metoncholai- 



mus is said by Filipjev (1918) to differ from Oncholaimus 



in having very long spicules and a " tubiform organ " of 



I different structure. These points, however, scarcely appear 



1 to warrant a generic distinction. We have been unable to 



'i find any satisfactory characters in Filipjev's (1924) diagnosis 



I to justify the separation of Adoncholaimus. Prooncholaimus 



Micoletzky is equally unsatisfactory. 



I ■ 2. Paroncholaimus Filipjev, 1916. 



According to Filipjev this genus differs from Oncholaimus 

 in the following characters. Of the teeth in the pharynx 

 the two subventral are symmetrical and larger than the dorsal. 

 In the female, a " tubiform organ " is absent. 



Hab. Marine. 



Genotype : P. [Oncholaimus] vulgaris (Bastian, 1865). 



Bastian, 1865, Trans. Linn. Soc. London, xxv, 135 ; Filipjev, 

 1916, Ann. Mus. Zool. Acad. Imp. Sci., Petrograd, xxi, 105. 



3. Oncholaimellus de Man, 1890. 



Head with ten bristles. PharjTix elongate, its anterior 

 - i third separated by a constriction from the posterior part. 



