THE CHIEF COKlSOriMSKOUS FAUN*. 



6] 



bar. For several years, while Mr. W. C. Thomson and the 

 late Mr. Wylie were stationed there, I was in the habit of receiv- 

 ing largo collections every year from that place ; and yet during 

 all that time and out of all that multitude I never saw aStaphy- 

 linidous insect among them. In other parts of the continent, 

 where, as at the Cape, they have been exposed to microtypal con- 

 tact they do occur, but in trifling numbers. Boheman mentions 

 thirty -eight in his ' Insecta CafFrariae." Natal and Mozambique 

 supply a very few more ; and Dr. Welwitsch found a few of the 

 same genera in Angola. Now India is as poorly supplied w T ith 

 them as Africa ; and the chief part of those found in both belong- 

 to such genera as Pccderus, Osorius, &c, which may possibly not 

 be microtypal. But there are true microtypal species, both of 

 Staphylinidae and other groups, which are not found in India and 

 yet occur in Africa, and which, I think, must therefore have been 

 introduced subsequently to the separation of India and Africa, as, 

 for example, Aleochara, Ci/mindis, AncJiomenus, Feronia, Bembidium 

 (see Boheman's 'Insecta Caffrariae and various others, some 

 of which will be found in the Table of the present distribution of 

 Miocene genera given in the Appendix. There are three ways 

 in which these may have made their entrance into Africa — (1) 

 by Nubia and Abyssinia, (2) by the connexion with South-west 

 Australia to which I have alluded, or (3) by the union with 

 Patagonia, which I think can scarcely be disputed. One or two 

 noteworthy peculiarities attend all these elements of mixture ; 

 viz. the comparatively small numbers of species which have suc- 

 ceeded in establishing themselves in the country or which have 

 become generally distributed ; the small progress which has been 

 made by them in penetrating into it and getting away from their 

 starting-point ; and the absence of amalgamation with the original 

 fauna on which they have been superinduced (which last is a strong- 

 argument against hybridization having any important part in the 

 creation of new species). To these we must add, as obviously 

 belonging to the same category, the remarkable disinclination or 

 difficulty which one established fauna shows or finds to passing 

 beyond its own limits into the territory of a neighbouring fauna, 

 although the barrier which formerly separated them (and was the 

 cause of them each having a distinct character) is now no more 

 than an imaginary line. In Africa we can perfectly put our 

 hands on the Abyssinian interlopers dropping in from the north- 

 east, some, like plants and insects on Alpine mountains elsewhere, 



