NO. 6 CLASSIFICATION OF NEMATODES FILIPJEV 3 1 



neural esophageal swelling is present in most forms, less conspicu- 

 ous, and sometimes undeveloped, in Anguillulinae, always very 

 prominent in Cephalobinae. The Anguillulinae are the most simple 

 forms, generally with an elongated, unarmed, well-developed buccal 

 capsule (fig. 61) ; it is probable that some forms with a narrow buc- 

 cal capsule acquired this secondarily. It is very probable that most 

 earthworm parasites should be annexed to the Anguillulinae.^ 



Besides the distinction mentioned in the structure of the esoph- 

 agus, there is another in the structure of the mouth capsule. In the 

 Anguillulinae its walls are for the most part built up of three parallel 

 uninterrupted plates. In the Cephalobinae there are several such 

 plates with a thinner cuticle between them. It is probable that the 

 chief plate of the Anguillulinae is homologous with only one plate of 

 the Cephalobinae; thus the mouth capsules of the two are not 

 homologous to each other. 



The peculiar genus Ccphalobium Cobb, parasites of the intestine 

 of Gryllidae, could be compared, from the tooth of the mouth cap- 

 sule and the preneural dilatation of the esophagus, with the Diplo- 

 gasterinae, but the muscular posterior part of the esophagus makes 

 this inclusion impossible. Therefore, the right place should be found 

 among the Anguillulidae. The several peculiarities of structure 

 make impossible the direct inclusion of it in the Cephalobinae, to 

 which it can be compared, and it requires a separate subfamily. I 

 do not find the position among the oxyurids proposed by Artigas 

 (1929) satisfactory. The body cavity parasites, Steinerneminae, are 

 better placed here than in the Oxyurids as proposed by Steiner. 



The little group of the Bunoneminae is very closely related to 

 the Anguillulinae. They are all moss-inhabiting species with two 

 rows of remarkable, asymmetrical, cuticular knobs on one side of the 

 body which thus becomes physiologically a ventral side, or other dif- 

 ferentiations of the cuticle, often of very strange appearance, and 

 with cephalic outgrowths (fig. 66). 



Here should be placed the digenetic Rhabdiasinae, parasites of 

 vertebrates. Baylis and Daubney gave them a place in the same sub- 



3 The nematodes of earthworms are too little known to be included in the 

 list directly. According to Pierantoni, they constitute a separate family, the 

 Drilonemidae Baylis and Daubney, 1926 (syn. Cephalonemidae Pierantoni). 

 The genera reported are: Drilonema Pierantoni, 1916; Mesonema Pierantoni, 

 1916; Opistonema Pierantoni, 1916; Pierantonia Baylis and Daubney, 1926 

 (syn. Cephalonema Pierantoni, 1916, preocc.) ; Pharyngonema Pierantoni, 

 1923; Dicelis Dujardin, 1845 (cf. Wiilker, 1926); Synoeconema Magalhaes, 

 1905 (syn. Dionyx Perrier, 1881, preocc). There must be added as a doubt- 

 ful genus Lwnbricicola Friedlander, 1895 (probably young Rhabditis larvae). 



