44 ZOOLOGICAL GEOGRAPHY. [part hi. 



intermingled in nearly equal proportions with forms derived from 

 Tropical America ; and the varying degrees of resemblances of 

 the Chilian to the northern species, seems to indicate successive 

 immigrations at remote intervals. 



Cohoptc.ra. — It is among the beetles of South Temperate 

 America that we find some of the most curious examples of 

 remote affinities, and traces of ancient migrations. The Carabidae 

 are very well represented, and having been more extensively col- 

 lected than most other families, offer us perhaps the most com- 

 plete materials. Including the Cicindelidse, about 50 genera are 

 known from the South Temperate Sub-region, the greater part 

 from Chili, but a good number also from Patagonia and the 

 Straits of Magellan. Of these more than 30 are peculiar, and 

 most of them are so isolated that it is impossible to determine 

 with precision their nearest allies. 



The only remarkable form of Cicindelidee is Agrius, a genus 

 allied to the Amblycheila and Omus of N.W. America. Two 

 genera of Carabidse, Cascellius and Baripus, are closely allied to 

 Promecoderus, an Australian genus; and another, Lecanomcrus, 

 has one species in Chili and the other in Australia. Five or six 

 of the peculiar genera are undoubtedly allied to characteristic 

 Palsearctic forms ; and such northern genera as Carahus, Pristo- 

 nychus, Anchomenus, Pterostichus, Percus, Bradycellus, Trechus, 

 and Bcynhidium, all absent from Tropical America, give great 

 support to the view that there is a close relation be- 

 tween the insects of the northern regions and South Temperate 

 America. A decided tropical element is, however, present. 

 Tropopterus is near Colpodes, a Tropical and South American 

 genus ; Mimodrtmiius and Plagiotelium are near Calleida, a 

 South American genus ; while Pachyteles, Pericompsus, Vario- 

 palpus, and Calleida are widely spread American groups. 

 The preponderance of northern forms seems, however, to be 

 undoubted. 



Six Carabidai are known from Juan Fernandez, 3 being 

 identical with Chilian species and 3 peculiar. As the island is 

 350 miles from the mainland, we have here a proof of how 

 readily insects may be transported great distances. 



