28 B. C. ENTOMOLOGICAL SOCIETY 



Mallophaga (Bird Lice) infest an Australian Cassowary and two of the 

 South American Rheas ; while two species of the same genus (Lipeurus) 

 are common to the African Ostrich and a third kind of South American 

 Rhea. These parasites must have been inherited unchanged by the 

 various members of these three families of flightless birds from their 

 common ancestors, that is from early Kainozoic times at latest. 



Handlirsch (4, p. 250) has shown in a summary of the distribution 

 of the species of existing and extinct genera of insects that heterometa- 

 bolus species are more numerous in warm regions, whilst holometabolic 

 species are more frequent in cold countries. Arguing from this fact, we 

 are led to the conclusion that those species, the fossil remains of which 

 are found in the rocks of temperate regions, but are related to forms 

 which today occur only in warm, southern countries, must have existed 

 at a time when temperature conditions were more favourable in those 

 regions where they now occur only as fossils. In amplification of the 

 evidence Handlirsch (3, p. 518) cites several cases and I take the oppor- 

 tunity of presenting a translation of his words: 



"The sand-ground beetle, Tetracha Carolina, occurs today only in 

 the southern part of North America and in Central America, but it is 

 also found in the European Bernstein. The sawflies of the genus Perga 

 exist today only in Australia and sparingly in South America. They 

 were, however, present in the Miocene of North America. The Aethio- 

 pian genus Glossina (tse-tse flies), fortunately now only represented in 

 tropical Africa, but they were present in the Miocene of North America. 

 The nemopterid genus Halter is now confined to the Eastern Alediter- 

 ranean, whereas species abounded in North American Miocene. Various 

 genera of ants which one finds today only in tropical Asia, lived in the 

 Oligocene in Northern Europe. 



"Not only do these fossil remains indicate a similarity in the environ- 

 mental conditions of the regions where they occurred thousands of years 

 ago with those that now prevail in those regions where their allies at 

 present live, but it is more than probable that there was distinct land 

 connections between the different continents in places now occupied by 

 the waters of the ocean. 



"It appears to me that generally speaking insects oiifer very good 

 evidence for the assumption that the northern continents were linked 

 up at diiTerent times to each other by means of land-bridges, for there 

 was in the Palaeozoic a great resemblance between the faunas of the 

 eastern and western hemispheres. All orders of which we have been 

 able to recognize more than one representative, have been shown to 

 occur both in America and Europe. Almost all families tolerably rich 

 in species, and many genera occur on both sides of the Atlantic, and 

 although the species often appear to be different, yet the difference in 

 the general facies of the faunas is certainly not any trreater than that 



