94 ECOLOGICAL FOUNDATIONS OF ZOOGEOGRAPHY 



astonishing number of languages are found on the Pacific slope of 

 the Andes while the rest of the continent has no more than a dozen 

 language groups. 79 



Australia affords the most complete example of the preservation 

 of archaic types. It is rightly called the land of living fossils. Here 

 are found the only egg-laying mammals, with two genera, Echidna 

 and Ornithorhynchus; with their numerous reptilian characters, these 

 are veritable "missing links." With them lives the greater proportion 

 of the surviving marsupials, which formerly ranged over Eurasia and 

 North America but are now restricted to the Australian series, to a 

 few South American genera, and to the North American opossum. 

 The isolation of Tasmania has even preserved two species of preda- 

 ceous marsupials, Thylacinus and Sarcophilus, which are extinct on 

 the Australian mainland, where their remains are found in the Pliocene 

 and Recent deposits in company with those of the dingo, which has 

 evidently replaced them. 80 Southern Australia and Tasmania harbor 

 survivors of the primitive crustaceans of the family Anaspididae, 

 consisting of 3 monotypic genera: Anaspides, Paranaspides, and Koo- 

 nunga. Their primitive character is shown by their relations with the 

 Palaeozoic genera Uronectes and Palaeocaris, and their intermediate 

 position between the two large and widespread orders, Schizopoda 

 and Arthrostraca. 



New Zealand is likewise the home of certain primitive relicts. 

 Sphenodon is the sole survivor of a formerly widespread order of 

 reptiles. Liopelma represents the most primitive of the families of 

 frogs. The most primitive of all Lepidoptera, the hepialid Palaemicra 

 calcophanes, lives here. It is so closely allied to the caddis-fly genus 

 Rhyaoophila that it almost forms a link between the two orders. 81 

 New Zealand and Australia are the home of the primitive mygalid 

 spider Hexathele. 82 



Underground caves are also a refuge for primitive forms. A large 

 proportion of the cave snails of the Balkan Peninsula, including the 

 genera Meledella, Pholeoteras, Phygas, and Spelceo concha, is entirely 

 unrelated to the present snail fauna of the surface and represents 

 a remnant of a fauna no longer existent there. 83 Animals of sub- 

 terranean waters are likely to be peculiar and primitive. The blind 

 cave salamander, Proteus anguineus, has no relatives in Europe. In 

 the same waters in which it occurs are found crustaceans of the genus 

 Troglocaris, of a group whose representatives are otherwise absent 

 in fresh waters in Europe. Bathynella nutans, found in deep wells at 

 Prague and Basel, is the only relative of the above-mentioned Ana- 

 spididae found outside of Australia. 84 



