IRONINAE 139 



26. Dorylaimopsis Ditlevsen, 1919. 



Cuticle striated, and marked with transverse and longi- 

 tudinal rows of dots. Head not distinct, with smooth cuticle 

 and a crown of short and stout bristles. Lateral organs large, 

 spiral. Pharynx apparently tubular, its walls presenting the 

 appearance of a protrusible " spear," but of quite different 

 structure from that of the Anguillulinidae. Oesophagus 

 swollen posteriorly, without bulb. Caudal end of male with 

 a median ventral row of preanal papillae and two sub ventral 

 rows of postanal bristles. Spicules rather long, bent almost 

 at right angles before the tip, and with a hook-shaped promi- 

 nence ventrally somewhat behind the middle. Two accessory 

 pieces present, the posterior with a posterior process. Female 

 genital tubes paired, opposed, outstretched. 



Hab. Marine. 



Genotype : D. punctatus Ditlevsen, 1919. 



Ditlevsen, 1919, Vid. Medd. Naturh. Foren., Copenhagen, 

 Ixx, 162. 



Subfam. 3. IRONINAE Micoletzky, 1922. 



Pharynx tjrpically elongate, tubular, with three, or a 

 multiple of three, teeth (sometimes eversible) near its anterior 

 end. Oesophagus club-shaped, usually without distinct bulb. 



1, Ironus Bastian, 1865. 

 Syn. Thalassironus de Man, 1889 ; Cephalonema Cobb, 

 1893, nee Pierantoni, 1916 ; Nanonema Cobb, in Stiles & 

 Hassall, 1905. 



Cuticle unstriated, without bristles or lateral alae. Head 

 with three lips and four submedian bristles. Lateral organs 

 variable. Pharynx long and narrow, with three strong hook- 

 shaped teeth at its anterior end, and three smaller denticles 

 a little further back. The lips are movable, allowing pro- 

 trusion of the teeth in the pharynx. Oesophagus gradually 

 swollen behind. Caudal end of male without papillae or with 

 a few ventral preanal bristles. Female genital tubes usually 

 paired, opposed. Some species are hermaphrodite (Cobb). 

 Caudal glands present. Spinneret absent. 



Hab. Fresh water and soil. 

 Genotype : /. ignavus Bastian, 1865. 



Bastian, 1865, Trans. Linn. Soc. London, xxv, 103 ; Cobb, 

 1893, Agric. Gaz. N.S.W., Sydney, iv, 825; Cobb, in Stiles & 

 HassaU, 1905, U.S. Dept. Agric, Bur. Anim. Indust. Bull. 79, 

 122; Micoletzky, 1922, Arch. f. Naturg., Abt. A, Ixxxvii, 323. 



de Man appears to have been influenced chiefly by the 

 marine habitat of the species britannicus in creating a new 



