ONCHOLAIMIDAE 109 



annulated, each ring bearing a circle of long, backwardly- 

 directed, pointed bristles. Among these bristles there are a 

 few stouter, tubular, subdorsal bristles resembling the ventral 

 ambulatory appendages of the Chaetosomatidae. Lips not 

 distinct. A minute pharjrnx apparently present. Oesoph- 

 agus with two slight swellings. Spicules very slender, 

 straight. Accessory piece apparently absent. Male genital 

 tube single, reflexed. Female genital tubes paired, opposed, 

 reflexed. Caudal glands and spinneret present. 



Hab. Marine. 



Genotype : O. [TricJioderma] oxycaudata (Greeff, 1869). 



Greeff, 1869, Arch. f. Naturg., xxxv, i, 115; Cobb, 1922, 

 Journ. Washington Acad. Sci., xii, 229 [Contr. Sci. Nematol., 

 xii]. 



5. Richtersia Steiner, 1916. 



Body short and stout. Head distinct, with lips (probably 

 six), papillae and bristles, and followed by a cuticular " collar." 

 Lateral organs spiral. Cuticle of body finely striated, with 

 numerous longitudinal rows of fuie, hook-like appendages, 

 and short, scattered bristles. The " collar " bears five longer 

 bristles. Pharynx narrow, with a peculiar " kink " in its 

 walls posteriorly. Oesophagus thick and muscular, without 

 bulb. Caudal end of male with preanal and postanal papillae. 

 Spicules slender. A forked accessory piece present. Female 

 genital tubes paired, opposed. Spinneret present. 



Hab. Marine. 



Genotjrpe : R. collar is Steiner, 1916. 



Steiner, 1916, Zool. Jahrb., Syst., xxxix, 583. 



Fam. 14. ONCHOLAIMIDAE nov. 



Typically small, free-living forms with a buccal cavity 

 having chitinoid walls and containing usually three teeth, 

 of which one is dorsal and two subventral. One or more of 

 the teeth may be absent, or additional teeth or denticles 

 may be developed. Oesophagus with or without a posterior 

 bulb. 



This group is nearly co-extensive with the family Odonto- 

 pharyngidae proposed by Micoletzky (1922). It contains 

 a large and heterogeneous collection of genera, very 

 difficult to arrange in a natural and satisfactory manner. In 

 Micoletzky 's system the family Odontopharyngidae was 

 divided into seven subfamilies (Ironinae, Enoplinae, Oncho- 

 laiminae, Microlaiminae, Chromadorinae, AnguiUulinae and 

 Diplogasterinae). On reviewing the whole of the genera, 

 we have found it possible to retain the three fijst-mentioned 

 subfamilies (their contents being somewhat altered), but 



