366 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



probably some of these will yet be found in Australia. One of these 

 (Myoectis) has been thus far reported only from the Aru Islands. As 

 Tasmania has two peculiar genera {Thylacinus and Sarcophilus), ^ew 

 Guinea, in view of its four or five times greater area, is in reality 

 scarcely more specialized than is Tasmania, and is hence faunally as 

 much a jjart of Australia as is the latter. As will be shown later, 

 nearly as many of the genera occurring in Southern Australia have 

 been found in New Guinea as in Tasmania. Scarcely two years ago Mr- 

 Wallace stated that " as yet no other [referring to the genus Sus] non- 

 marsupial terrestrial mammal has been discovered [in " Papua, or the 

 New Guinea Group "] except a Eat, described by Dr. Gray as Uromys 

 aruensis, but about the locality of which there seems some doubt."* 

 This genus has not only now been established as occurring there, but 

 four additional species of it have been described by Dr. Peters, who 

 has also added a species of Sydromys, and Mr. Alston has added a 

 species of Mus and M. A. Milne-Edwards a species of Sapalotis, in all 

 seven species, belonging either to Australian genera or having decided 

 Australian afiQnities. 



Regions of the Australian Realm. — Accepting the Polynesian Islands 

 as forming one region (the Polynesian), and New Zealand as consti- 

 tuting another (the New Zealand), we have left for detailed considera- 

 tion only the larger land-masses, consisting of Tasmania, Australia, and 

 New Guinea with its associated islands, forming the third or Australian. 

 The close zoological affinity of Tasmania and Australia no one ques- 

 tions, and it has been already shown that New Guinea and Australia 

 are almost equally inseparable. Although many genera range from 

 Tasmania across Australia into New Guinea, this large area, embra- 

 cing as it does nearly fifty degrees of latitude, falls naturally into two 

 ■well-marked subdivisions, the one tropical the other temperate.t These 



* Geogr. Distr. Anim., vol. i, pp. 409, 410. 



tin 1871, in referring to the Australian Realm (Bull. Mus. Comp. Zo61.,vol. ii,p. 

 381), I said : — " It is divisible into a Temperate and a Tropical Region, the former em- 

 bracing New Zealand and Australia." The latter portion of this statement was of 

 course made without due consideration. As already stated, New Zealand has no inti- 

 mate relationship with Australia, and should be treated as a separate and independent 

 region of the Australian Realm. Mr. Wallace, in stating his " Objections to the Sys- 

 tem of Circumpolar Zones" (Geogr. Distr. Anim., vol. i, p. 67), has very naturally taken 

 notice of this unfortunate slip, and cites it as evidence of the ''erroneous results" 

 that follow from the adoption of the principle of the "distribution of life in circum- 

 polar zones". My " separation of New Zealand to unite it with the southern third of 

 Australia " was certainly most thoroughly erroneous ; but while, as Mr. Wallace says, 

 the fauna of Australia, taken as a whole, js exceptionally homogeneous, I cannot agree 

 with him that New Guinea, so far at least as its mammalian fauna is concerned, is '' as 

 sharply differentiated from Australia as any adjacent parts of the same primary zoologi- 

 cal region can possibly be" — in other words, that it can be only arbitrarily joined with 

 the northern portion of Australia. I freely admit that I was not only in error as re- 

 gards New Zealand, but also in respect to my division of the Australian continent, and 

 I accept this portion of Mr, Wallace's criticism as fairly made. That the error was 

 not one of " principle ", but merely a wrong application of a principle,! think the text 



