THE CHIEF COLEOPTEROUS EAUK^. 45 



I suppose I may assume that if the present position of Eucra- 

 nium is due to a former union of Patagonia with Africa prior to its 

 existence, the same conclusion applies to Agrius and the Rhea. 

 We do not require a separate Deus ex machind, a separate 

 junction of Africa and Patagonia for each of these desert species. 

 Had any of them been of a constitution inconsistent with exist- 

 ence in a desert, we might have had to do so ; but all three being 

 by nature denizens of that kind of country, one explanation, one 

 resource will do for all. 



The next question in I'elation to them is in what direction the 

 union of land lay by which the species travelled from Africa to 

 South America, and by what route they reached their present 

 locality. They may have come vid the South Pole or Cape 

 Horn, and having been established in a southern (now vanished) 

 laud, spread north to their present locality ; or they have come in 

 by Brazil and spread south to it ; or their present habitat may be 

 merely the inner margin of a wider former stretch of plains reach- 

 ing all the way straight across the Atlantic. It may be that a 

 former land once existed there where the plains of the Pampas 

 now lie. The present Patagonia may not be the first of the kind, 

 although the first of the name. This may be actually Patagonia 

 the second, or, for aught we know, Patagonia the third. Mr; 

 Darwin tells us of what must have been more than one previous 

 Patagonia submerged and destroyed. " It required little geological 

 practice," says he, " to interpret the marvellous story which this 

 scene at once unfolded." (He is looking at some petrified trees on 

 a bare slope of the Andes at an elevation of 7000 feet, near Men- 

 doza. ) "I saw the spot where a cluster of fine trees had once 

 waved their branches on. the shores of the Atlantic when that 

 ocean (now driven back 700 miles) approached the base of the 

 Andes. I saw that they had sprung from a volcanic soil which 

 had been raised above the level of the sea, and that this dry land, 

 with its upright trees, had subsequently been let down to the 

 depths of the ocean. There it was covered by sedimentary matter, 

 and this again by enormous streams of submarine lava, one such 

 mass alone attaining the thickness of 1000 feet ; and these de- 

 luges of melted stones and aqueous deposits had been five times 

 spread out alternately. The ocean which received such masses 

 must have been deep ; but again the subterraneous forces exerted 

 their power, and I now beheld the bed of that sea forming a chain 

 of mountains more than 7000 feet in altitude." (Darwin, ' Journal,' 



