ACARINA FROM THE JUAN FERNANDEZ ISLANDS 



619 



In the present species the demarcation line between the anal shield and 

 the ventral shield is very indistinct even in specimens treated with caustic soda. 

 Berlese considers the absence of a metapodial line as typical (1. c. p. 249) 

 »Metapodia intersese concreta, ventrem obtegentia», but at the same time he 

 admits into the genus a species, U. elimata, which he characterizes in the fol- 

 lowing way (Acari Mirmecophili p. 337): »La Urobovella elimata che dififerisce 

 anche per altri caratteri dalle tipiche, presente una specie di linea metapodica 

 dietro le zampe del 4° paio, ma ha visibilissima I'incisione tra lo scudo ven- 

 trale e I'anale*. 



In the present species the metapodical line is very fine but quite distinct 

 in specimens treated with caustic soda. 



It differs, however, from Urobovella by the two low, anteriorly converging 



Figs. 148 — 149. Urobovella bicarinata n. sp. 

 148. Dorsal view cf. 149. Ventral view cf. 



dorsal ridges in the posterior half of the dorsal shield, a feature which is met 

 with in Urodinychiis, and from all known Uropodidae by the extremely peculiar 

 shape of the appendage of the mandibles of the male. The mouth-parts of 

 the Uropodide are, however, too imperfectly known to enable us to draw any 

 conclusions from this feature. 



Male. 



Length 1040 [i, width 740 \^. 



Colour chestnut brown. 



Texture polished. 



Shape oval, pointed posteriorly, blunt anteriorly. 



The dorsal side (fig. 148) is covered by a large, central shield and a 

 narrow, marginal shield which tapers considerably towards the posterior end 

 and is coalesced with the central shield near the anterior end. The dorsal 

 shield, shows, when the mite is treated with boiling lactic acid, an extremely 

 finely punctured surface, the punctures being arranged in concentrical rows. 



