THE GENUS LEBBRTIA. 483 



the text only refers to swimming hairs on the two posterior pairs. 

 Based on the capture of specimens of Lebertia at Zweibriicken 

 (Koch's locality), which Thor believes to be identical with Koch's 

 species, Thor has redescribed the species as Lebertia inaequalis 

 (Koch, 1837) Sig Thor, 1900. This has been acknowledged as 

 valid by Continental writers, for records have appeared since 

 then from Switzerland, Italy and even from Turkestan. 



As to the grouping of the component genera of the Hydra- 

 carina, various suggestions have been made. These have been 

 discussed by Wolcott in his Review of the Water Mites* In 

 his classification he groups Nilotonia, Lebertia, Oxus, Frontipoda, 

 and Gnaphiscus as sub-family Lebertiinae. In Koenike's later 

 classification f the sub-family Lebertiinae covers the last four 

 of these genera, Nilotonia being transferred to another sub- 

 family. Thor's Prodromus,% published in 1900, included several 

 other genera in addition to those noted by Koenike, and these 

 Thor designated as Family Lebertiidae. The Prodromus does 

 not discuss the matter, and owing to this want it does not appear 

 to have obtained favour among acarologists. Probably Koenike's 

 classification may be found to represent more closely than 

 hitherto the natural grouping of the genera, but until we know 

 more of the larval forms a definite expression of opinion must be 

 postponed. 



Sig Thor makes some interesting reflections on the phylogeny 

 of Lebertia. In the absence of a sufficient knowledge of the 

 larvae, he has had recourse to the nymphal forms in conjunction 

 with the imagines for clues as to what course the line of descent 

 might take. He conceives a hypothetical form Urolebertia, from 

 which spring two other hypothetical forms, Protoxus and Proto- 

 lebertia the former leading up to Gnaphiscus, Oxus and Fronti- 

 poda, and the latter to the sub-genera of Lebertia. Of these, 

 Pseudolebertia, Hexalebertia and Mixolebertia are the three 

 branches which have a common hypothetical ancestor in 

 Protolehertia. Descent is continued into Pilolebertia and Lebertia 

 ( = Neolebertia), the former appearing to have qualities which 

 may be designated as of a dominant and the latter of a recessive 

 type. 



* Trans. Amer. Micro. Soc., xxvi. 205. 



f Abh. Nat. ver. Bremen, xx. 144. 



% Nyt. Mag. / 'or Nature., xxxviii. (3), 263-266. 



