138 ASCAROIDEA 



The status of this genus appears very unsatisfactory. It 

 was originally based on a single male specimen of the genotype 

 and the female of a second species, contortus. To these the 

 third species, septentrionalis, was added in 1914, and this 

 differs in several respects from the others (single accessory 

 piece, paired testes, ovaries outstretched instead of reflexed, 

 etc.). In the figure of the genotype no pharyngeal cavity is 

 shown, and the presence of a pharyngeal tooth seems, in any 

 case, to be rather uncertain. 



24. Xanthodora Cobb, 1920. 



Cuticle coarsely striated, except on the head. Head not 

 distinct, with three lips and a crowii of twenty-six short, stout 

 bristles, arranged in groups. Lateral organs incipient spirals. 

 Pharynx apparently narrow and elongate, containing a single 

 dorsal, anteriorly-directed tooth. Oesophagus with a con- 

 striction immediately behind the pharynx, and gradually 

 swollen behind, where it is divided by breaks in the muscula- 

 ture into three regions of unequal length, the anterior the 

 longest. Caudal end of male with six preanal supplementary 

 organs, and additional nerve-endings between them. Spicules 

 tapering towards each end. Accessory pieces inconspicuous 

 except for their distal portion. Testis probably single, 

 anterior, outstretched. Female genital tubes paired, opposed, 

 reflexed. Ova " occur in the uteri one at a time." Caudal 

 glands and spinneret present. 



Hab. Marine. 



Genotype : X. nuda Cobb, 1920. 



Cobb, 1920, Contr. Sci. Nematol., ix, 317 and key. 



25. Choniolaimus Ditlevsen, 1919. 



Cuticle striated, apparently without bristles except for a 

 single ring in the constriction behind the head. Head trun- 

 cate, separated by a shallow groove. Lateral organs large, 

 spiral. Pharynx funnel-shaped, without teeth. Oesophagus 

 with a distinct posterior bulb. Caudal end of male with 

 thirteen ventral preanal supplementary organs. " Accessory 

 piece (or pieces ?) embracing the tips " of the spicules like a 

 sheath. Female unknown. (Genus based on a single male 

 specimen) . 



Hab. Marine. 



Genotype : C. j)(ij>ill(itiis Ditlevsen, 1919. * 



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

 Ixx, 185. 



Ditlevsen expresses the view that possibly this form will 

 prove to be related to Chromadora. 



