154 BARBOUR: ZOOGEOGRAPHY. 



tions of the birds. Hutton and Drummond (Animals of New Zealand, 1905, 

 p. 19-20) ask the question: — "Why should some of the shore birds and the two 

 Cuckoos migrate to New Zealand, while the Swallows, which are certainly quite 

 as capable of undertaking the journey, do not come?" Possibly the answer may 

 be found in the palaeontological history of birds. The evidence is of a negative 

 character, and must be used with great caution; but it seems probable that the 

 Godwit and the Cuckoo migrated to New Zealand at a time when there were no 

 swallows in existence, and that the original land-bridge had been completely 

 broken down before the first of the swallows arrived in Australia from Asia. We 

 may therefore suppose that migration to and from New Zealand commenced 

 in the Eocene period, when the land stretched away northwest to New Guinea, 

 a time when all New Zealand was joined to the mainland. 



Papuasia, judging from its markedly peculiar bird fauna, consisting of an 

 enormous number of species and genera, and its peculiar amphibians and insects, 

 and especially its Onychophora, would warrant its being considered a zoological 

 province almost as well differentiated as that which we have always called the 

 Australian, and quite distinct from this. It received some characteristic Austra- 

 lian types from among those able to distribute themselves quickly, owing to a 

 short-lived communication with Australia (excluding Queensland) which we 

 have discussed. This increment has not fundamentally affected the facies of 

 the fauna of the region. 



The fauna of western Australia was received by a land connection with Asia 

 quite independent of the Papuan-Queensland bridge, if it is necessary to suppose 

 that Australia was ever really connected with Asia. Such a connection may have 

 had relation to the ancient arc of which Timor and Sandalwood Island are but 

 the last remaining vestiges. These islands do not belong to the actively volcanic 

 arc of the Lesser Sunda Islands, and have a different geologic structure. This 

 ancient arc, too, may have led into the region of Java, and so had relation to the 

 mainland. The islands west of Sumatra do not show evidences in their reptiles 

 and amphibians of having formed a continuation of this arc, and of having thus 

 formed a link between Java and the Malayan or Burmese continental region 

 parallel to, but independent of, Sumatra. There is no hydrographic evidence of 

 such a connection; and, though at one time it was thought that the land shells 

 of Engano were more like those of Java than of Sumatra, this was undoubtedly 

 due to the fact that we then knew but little of the fauna of Sumatra, while Engano 

 had been visited by several collectors. Rana microdisca Boettger was formerly 

 thought to have had a similar distribution, but it has since been found quite 



