148 ASCAROIDEA 



present, with lenses. Male with two complex accessory 

 pieces ( ?). Female genital tubes paired, opposed, reflexed. 

 Caudal glands and spinneret present. 



Hab. Marine. 



Genotype : R. morstatti Marion, 1870. 



Marion, 1870, Ann. Sci. Nat., Paris, Zool., (5) xiii, Art. 14, 31. 



It is difficult to draw up an intelligible diagnosis of this 

 genus from the description given by Marion, which is some- 

 what obscure and occasionally self-contradictory. Although 

 the structures connected with the pharynx are stated to be 

 paired, it seems very probable that they are in reality tri- 

 radially an'anged. In his brief generic diagnosis Marion states 

 that there are two longitudinal accessory pieces in front of the 

 spicules, and two other median pieces. In the specific descrip- 

 tion of the type, however, he mentions two lateral, bifid, 

 accessory pieces and one median piece. The figure suggests 

 two accessory pieces, each with three sharp, forwardly- 

 directed processes. 



9. Cheironchus Cobb, 1917. 



The only available diagnosis of this genus is contained in 

 the legend to a figure and in the " formula " of the genotype. 

 The genot3rpe is said to be " A nema whose bilaterally sym- 

 metrical mandibles have arisen from the ventrally submedian 

 sectors of the head at the same time that the dorsal elements 

 of the pharynx have disappeared. Cheironchiis has the general 

 appearance of Selachinema, but has no vestigial dorsal jaw, 

 and presents both pharyngeal and cardiac bulbs." According 

 to the formula, the testes are paired, opposed, outstretched ; 

 the female genital tubes paired, opposed and reflexed. Spin- 

 neret present. 



Hab. Not mentioned. 

 Genotjrpe : C vorax Cobb, 1917. 



Cobb, 1917, Contr. Sci. NematoL, v, 119. 



Appendix to Oncholaimidae. 

 The following forms are of uncertain position. 



a. Heterocephalus Marion, 1870, nee Riippel, 1842. 



Head suddenly narrowed, distinct, truncate, surrounded by 

 a crowTi of stout, recurved bristles. Buccal cavity rather 

 large, armed with chevron-shaped cuticular thickenings. 

 Two long, slender spicules, strongly denticulate on their 

 lower surfaces near the tips. A " roof -shaped " accessory 

 piece present. A single preanal supplementary organ present 



m 



