42 ZOOLOGICAL GEOGRAPHY. [part in. 



The Neotropical genera of Earddge, five of which extend to 

 Chili and Patao'onia, beloncj to a division which is Australian 

 and Neotropical, and wliich has species in the Oriental and 

 Ethiopian regions. 



Fresh-waUr Fishes. — These present some peculiar forms, and 

 some very interesting phenomena of distribution. Tlie genus 

 Percilia has been found only in the Eio de Maypu in Chili ; and 

 Pcrcichthys, also belonging to the perch family, has five species 

 confined to the fresh waters of South Temperate America, and 

 one far away in Java. Nematogenys (1 sp.) is peculiar to Chili ; 

 TricJwmyder us reaches 15,000 feet elevation in the Andes, — both 

 belonging to the Siluridre ; Chirodon (2 sp.), belonging to the 

 Characinidai, is peculiar to Chili ; and several other genera of the 

 same family extend into this sub-region from Brazil. The family 

 Haplochitonidffi has a remarkable distribution ; one of its genera, 

 HaplocMton (2 sp.), inhabiting Tierra del Fuego and the Falkland 

 Islands, while the other, Frototroeics, is found only in South 

 Australia and New Zealand. Still more remarkable is Oalaxias 

 (forming the family Galaxidas), the species of which are divided 

 between Temperate South America, and Australia, Tas- 

 mania, and New Zealand ; and there is even one species 

 (Galaxias atienuatas) which is found in the Chatham Islands, 

 New Zealand, and Tasmania, as well as in the Falkland 

 Islands and Patagonia. Fitzroya (1 sp.) is found only at 

 Montevideo ; Orcstias (6 sp.) is peculiar to Lake Titicaca in the 

 high Andes of Bolivia; Jcmjnsid (1 sp.) in the Ptio de la Plata 

 — all belonging to the characteristic South American family of 

 the Cyprinodontida3. 



Insects. — It is in insects more than in any other class of animals, 

 that we find clear indications of a not very remote migration of 

 northern forms, along the great mountain range to South Tem- 

 perate America, where they have established themselves as a 

 prominent feature in the entomology of the country. The 

 several orders and families, however, differ greatly in this 

 respect ; and there are some groups which are only represented 

 by modifications of tropical forms, as we have seen to be almost 

 entirely the case in birds and reptiles. 



