54 HEDLEY : MOLLUSCA OF THE ORIENTAL REGION". 



is as integral a part of the Oriental Region as any of its 

 recognised sub-regions ; and that, on the other hand, as great 

 a difference parts the Australian, from the Papuan sub-region as 

 intervenes between any two regions. The Papuan tract agrees 

 with the Oriental, in its characteristic wealth of operculates and 

 Naninidae, and disagrees with the Australian, in the presence of 

 these two and in the comparative absence of the Rhytididae, the 

 Endodontidae and the Acavinae. 



I wrote in 1891 '•'" Wallace's line, so conspicuous a severance 

 among the vertebrates, appears to be quite blotted out when the 

 distribution of animals is regarded from a molluscan standpoint. 

 No sharp break occurs between the Malayan fauna as exemplified 

 in Borneo or the Philippines and in New Guinea. All the 

 characteristic Malaya-n forms, Atopos, Xesta, Helicarion, Micro- 

 cystina, Trochomorpha, Ohha, Clilovitis, Cochlostyla, Pupina and 

 Diplommatina, are common to both regions. The Solomon 

 Islands, Fiji, &c., appear by the light of the Papuan shells to be 

 inhabited by an eastern extension of this Malayan fauna, which 

 has also overflowed into Queensland." Wider knowledge has 

 since strengthened my belief in the correctness of this estimate, 

 and recently I have been gratified to receive support I from so 

 high an authority, and one so well acquainted with the 

 Malayan fauna, as Dr. \'on Moellendorff. 



Botanists confirm the homogeneity of the province as thus 

 expressed, for Hemsley writes, [ " There is no doubt that the 

 combined Fijian, Samoan and Tongan flora is eminently Malayan 

 in character." For the correspondence between the Bornean 

 and the Papuan floras see Dr. O. Stapf's paper. ^ 



Mr. Cooke's summing {' of the Papuan fauna much 

 exaggerates its Australian tinge. We read that Rliytida 

 " emphasises this union still further." But Rhytida is Alpine in 

 New Guinea and only "unites" these two countries as an 

 Alpine Gentian' might "unite" Italy with Iceland. The 

 Pedinogym would indeed be — if it were not mythical — a strong 

 link. That Perrievia inhabits both Queensland and New Guinea 

 is hardly to the point, since, as Mr. Cooke admits, it has migrated 

 southwards from the one to the other. Of the characteristic 

 Australian genus Hadra, Mr. Cooke quotes (presumably from my 

 article) four Papuan species. After dissection and closer 



* P.L.S.N.S.W. (2), vi., p. 693. 



t Pro. Malac. Soc , I., p. 234. 



t Journ. Linn Soc , Botany, xxx,, p. 211. 



§ Trans. Linn. Soc , 2nd Ser., Botany, vol. iv,, pt. 2. 



II Of " Molluscs," Cambridge Natural History, vol. iii. 



