GG MB. A. MUEHAT on the GEOaUAPHICAL helations oe 



generally : speaking, it is not difl&cult to suggest tlieir source. 

 This absence of microtypal Brazilian forms is shown in a remark- 

 able manner by the Staphylinidae, an immense family which, as I 

 have already shown, is (wdth the exception of one small branch of 

 it which has found its way into India and East Africa) now en- 

 tirely confined to and very characteristic of microtypal lands. I 

 have explained that that family is entirely absent in Old Calabar ; 

 and I believe it is equally so throughout "West Africa. In the 

 Brazilian district, on the contrary, it is widespread, and in some 

 places abundant, especially Columbia and the districts adjoining 

 the Andes. It would seem to follow from this, that the union 

 between "West Africa and Brazil must have existed and been 

 brought to'a close before Brazil itself received its microtypal ele- 

 ment, at all events before it possessed StaphylinidiB, which seem 

 to have been a late acquisition. There was thus a time when 

 the Brazilian Coleopterous fauna was of pure unmixed type 

 of the same character as that which it has communicated to 

 "West Africa; in other words, I have been right in classing 

 the Brazilian as a great distinct stirps. That period must have 

 been prior to its union witb tbe rest of Soutli America ; for all 

 round it is microtypal ; and it must have been prior to its ex- 

 istence as an island, which, on other grounds, we know to have 

 been a phase through which it passed. I have, in my ' Geogra- 

 phical Distribution of Mammals,' given a map which shows the 

 form through which it probably passed when it and Venezuela 

 and Guyana were islands — a separation which created subfauuas 

 which still subsist, well marked and well defined, although the 

 general type is unmistakably the same. 



The way in which I read its history by these lights is : — first, that 

 a great continent extended across what is now the Atlantic, from 

 Brazil to "West Africa, shut ofi" by an ocean from the Andes or 

 nearest land to the west (wherever that may have been), on the 

 one hand, and from Eastern and Southern Africa, on the other; that 

 this continent next sank in the middle and the Atlantic took its 

 place ; that, according to the laws of gravity and equilibrium, as 

 its centre sank, its two ends and their shores rose, uniting West 

 Africa to the rest of its continent, and Brazil to the Aiidcs or 

 western microtypal land. And as the sea-bed to the west became 

 bare and dry, the Staphylinidae and other microtypal forms rushed 

 in from the west and the Brazilian types from the east ; and, the 

 groiind being free, both established themselves together, under the 



