UNRECOGNIZABLE FORMS 251 



cavity of the beetle, Passalus. In all probability it is a 

 Spirurid larva, but Leidy's description and figures do not 

 enable us to determine its position. 



Leidy, 1852, Trans. Amer. Phil. Soc, Philadelphia, n.s., X, 

 241; Diesing, 1861, Sitz. k. Akacl. Wiss., Wien, xlii, 728. 



31. Urolabes Carter, 1858. 



" The largest specimens are one-sixth of an inch long, 

 bilabiate, with an exsertile, sharp-pointed oesophagus ; the 

 hepatic sheath ending some distance from the termination of 

 the intestine ; the vulva opens in the female a little in front of 

 the middle of the body, and the anus posteriorly, just before 

 the body terminates suddenly in a whip-like tail. The penis 

 in the male is exsertile from the anus, very nearly close to the 

 posterior extremity of the body, which is so obtuse as to be 

 almost truncated." 



Hab. Fresh water. 



Genotype : U. 'palustris Carter, 1858. 



Carter, 1858, Ann. Mag. Nat. Hist., London, (3) i, 414. 



According to Micoletzky (1922, Arch. f. Naturg., Abt. A, 

 Ixxxvii, 442), the genotype of Urolabes is doubtfully referable 

 to Dorylaimus, all the other species being unrecognizable. 



C. UNRECOGNIZABLE FORMS. 



The following names occur in the literature of the Nematoda, 

 but cannot be recognized as valid genera. Some of them 

 are nomina nuda, while others refer to objects which do not 

 appear to have been Nematodes. 



1. Chaos Linnaeus, 1767. 



Although this genus included the worm kno■w^l as Anguillula 

 rediviva, it has as its type a Protozoan form, and cannot there- 

 fore be recognized as a genus of Nematoda. 



2. Crinon Chabert, 1782. 



Syn. Crino Lamarck, 1801 ; Crinola Rafinesque, 1815. 



This is unrecognizable as a genus of Nematoda, but is 

 possibly in part a synonym of Setaria. 



Chabert, 1782, Traite des maladies vermineuses, Paris, 21 ; 

 Lamarck, 1801, Systeme des Animaux sans Vertebres, Paris, 

 339. 



3. Diplasia von Holten, 1802. 



The name Diplasia trichiuri was given by von Holten (1802, 

 Skr. af Naturh.-Selsk., Copenhagen, v, 27) to a worm found in 

 the abdominal cavity of a fish. As Stiles & Hassall (1920) 



