HISTORICAL ZOOGEOGRAPHY 113 



The relatives of both of these groups are well represented among the 

 North American and European Tertiary fossils. The iguanid lizards 

 have their headquarters in South America and southwestern North 

 America, with a single genus in the Fiji Islands and two in Mada- 

 gascar. Their fossil remains are found in the European and North 

 American Eocene. 45 The giant water bugs of the genus Belostoma are 

 widely distributed in America, Africa, southern Asia, and Australia. 

 An isolated species in Dalmatia testifies to the former continuity of 

 this range, and fossil belostomas are known from the European Miocene 

 and Jurassic. 46 The gasteropod genus Gundlachia lives in Australia, 

 New Zealand, and South America. It is found as a fossil in the lower 

 Miocene near Frankfurt-am-Main. 4T 



The original continuity of the ranges of southern animals, now 

 discontinuous, is made very probable by such fossil records. Other 

 examples of discontinuity in groups in which no fossil evidence is 

 available may be interpreted in the same way. Thus the worm-like 

 amphibians, the caecilians, are confined to Africa, the Seychelles, 

 southern Asia and the East Indies, and tropical America. The South 

 American boid snakes of both Constrictor and Boa have representatives 

 in Madagascar. The only spiders with a segmented abdomen, an un- 

 mistakable primitive character, are found in Guinea and on the 

 Amazon. 48 Many genera of insects are restricted to the southern 

 hemisphere where their range is discontinuous. The Orthoptera Litur- 

 gousa, Stegmatoptera, and Pauletica occur in South America and in 

 Madagascar. The carabid genera Drimostoma and Homalosoma are 

 found in Madagascar, Australia, and New Zealand. Many genera of 

 ants are confined to the southern continents. The Onychophora, 

 Peripatus and its relatives, are found in Australia and New Zealand, 

 East Indies and southeastern Asia, South Africa, and tropical America, 

 including the West Indies. 49 The ancient earthworm genus Notiodrilus, 

 from which the widespread family Acanthodrilidae may be derived, 

 has a genuine relict distribution. It is found in New Zealand and the 

 Chatham and Snares islands ; in New Caledonia ; in the isolated oases 

 of central and northwestern Australia, in southernmost Africa, with 

 a species possibly in the Cameroons, in southern South America, and 

 finally in the Central American Cordillera. 50 The imperfection of the 

 palaeontological record makes it probable that the absence of fossils 

 in these groups means merely that they are not yet found or have not 

 been preserved. 



Some of the regional fresh-water animals, as distinguished from 

 universal forms, are also confined to the southern hemisphere with 

 discontinuous distribution on the various land masses and islands. 



