242 APPENDIX TO NEMATODA 



5. Synoecnema Magalhaes, 1905. 



Sjrn. Dionyx Perrier, 1881, nee Le Peletier & Serville, 1825. 



Mouth subterminal, apparently usually turned dorsally, 

 and overhung by two lateral, recurved, chitinoid hooks spring- 

 ing from its anterior (ventral) margin. Oesophagus club- 

 shaped. Tail of male relatively long and tapering. Two 

 short, stout spicules and a broad, triangular accessory piece 

 iisuaUy present. Vulva in the anterior half of the body. 

 Sexes sometimes permanently in cojiula. 



Hab. In cysts in the musculature, or free in the coelomic 

 cavity, of Earthworms. 



Genotype : S. [Dionyx] lacazii (Perrier, 1881). 



Perrier, 1881, Arch. Zool. exp. et gen., Paris, ix, 242; 

 Magalhaes, 1905, Arch. Parasitol., Paris, ix, 315; Pierantoni, 

 1910, Boll. Soc. Nat. Napoli, xxviii, 148. 



The name Dionyx being preoccupied, it seems legitimate to 

 adopt Synoecnema Magalhaes as the generic name. We 

 have, however, retained Dionyx lacazii Perrier as the genotype. 



B. GENERA INCEPvTAE SEDIS. 



The following genera are either so anomalous in structure 

 or so imperfectly described that it is impossible at present 

 to determine their affinities. 



1. Agamonematoideum Diesing, 1853. 



This name was given by Diesing {Sitz. k. Akad. Wiss., 

 Wien, X, 35) to a larval form found in a beetle {Blaps mortisaga). 

 According to Seurat (1916, Bull. Sci. France et Belg., xlix, 351) 

 this is probably the second-stage larva of a species of 

 Go7igylonema. 



2. Amblyura Ehrenberg, in Hemprich & Ehi-enberg [1828], 



1831. 



Body filiform, smooth. Head not distinct, truncate. Mouth 

 circular, surrounded by bristles. Tail tapering, slightly 

 swollen at the tip by the presence of a spimieret. Male with 

 a single spicule. Vulva in the middle of the body. Female 

 genital tubes paired. 



Hab. Fresh water ( ?). 



Genotype : Probably A. [Vibrio'\ serpeyitulus (Miiller, 1773). 



Miiller, 1773, Vermium terrestrium . . . Historia, 42 ; 1786, 

 Animalcula Infusoria, etc., 61 ; Hemprich & Ehrenberg [1828], 

 1831, Symbolae Physicae (Evertebrata), Ser. Prima, sig. a 

 (unp.). 



