296 The Naturalist in La Plata. 



portion of America,. The vizcacha does not benefit 

 himself alone by his perhaps unique style of 

 burrowing; but this habit has proved advantageous 

 to several other species, and has beon so favour- 

 able to two of our birds that they are among the 

 most common species found here, whereas without 

 these burrows they would have been exceedingly 

 rare, since the natural banks in which they breed 

 are scarcely found anywhere on the pampas. I 

 refer to the Minera (G-eositta cunicularia), which 

 makes its breeding-holes in the bank-like sides of 

 the vizcacha' s burrow, and to the little swallow 

 (Atticora cyanoleuca) which breeds in these ex-, 

 cavations when forsaken by the Minera. Few old 

 vizcacheras are seen without some of these little 

 parasitical burrows in them. 



Birds are not the only beings in this way related 

 to the vizcachas : the fox and the weasel of the 

 pampas live almost altogether in them. Several 

 insects also frequent these burrows that are seldom 

 found anywhere else. Of these the most interesting 

 are : — a large predacious nocturnal bug, shining 

 black, with red wings ; a nocturnal Oicindela, a 

 beautiful insect, with dark green striated wing-cases 

 and pale red legs ; also several diminutive wing- 

 less wasps. Of the last I have counted six species, 

 most of them marked with strongly contrasted 

 colours, black, red, and white. There are also 

 other wasps that prey on the spiders found on the 

 vizcachera. All these and others are so numerous 

 on the mounds that dozens of them might there be 

 collected any summer day ; but if sought for in 

 other situations they are exceedingly rare. If the 



