with one or perhaps two species, is peculiar to the Philippines, where 
also Urodiscus (a subgenus scarcely separable from Prioniturus) 
occurs *. But on crossing the Straits of Macassar and Lombock, 
which, as Mr. Wallace has well shown (Proc. Linn. Soc. iv. p. 172), 
form the boundary between the Indian and Australian regions, we 
meet at once with a strange contrast. In theislands scattered between 
this limit and the northern coast of Australia, not less than seventeen 
different genera of Psittacide occur ; and among them are two very 
peculiar types, the Cacatuine and Trichoglossine, which, as Mr. 
Wallace has observed, “‘ extend up to the extreme limits of the region 
without a solitary species passing over into the Indian islands of the 
Archipelago.” 
The distribution of the Psittacide in this region is further of great 
interest as exhibiting numerous instances of that well-known prin- 
ciple of geographical distribution according to which different hori- 
zontal areas are tenanted by closely allied and corresponding, though 
different species of the same generic type. The Psittacide, both in 
the Old and New World, appear to be especially subject to the in- 
fluence of this law +. Scarcely an instance is known of a bird of 
this family having an extended geographical range, and experience 
teaches us to be very suspicious of any supposed instance of the 
occurrence of the same species of Parrot in two localities of any 
distance apart. Mr. Wallace tells us that even between the Lorius 
garrulus of Gilolo and that of Batchian “there is a constant differ- 
ence in the size of the dorsal yellow patch ft.” 
The accurate working-out of the range and localities of the whole 
family would form a valuable contribution to our knowledge of 
zoological geography. There are, however, many species of the true 
habitats of which we are still ignorant. It is with the hope of 
being of some use to Mr. Wallace in his endeavours to increase our 
knowledge of this subject, that I have drawn up the Table I now 
exhibit. It is an extension of a somewhat similar one given in the 
zoological volume of the ‘ Verhandelingen.’ Many additional locali- 
ties have been ascertained by examination of the marked specimens 
in the Collection of Leyden, to which, through the courtesy of Pro- 
fessor Schlegel, I have always had unrestricted access during my 
visits to that city. 
In the following lists of the species inhabiting the different islands, 
I have given the Museums where the specimens are to be found, and 
the names of the collectors, when ascertainable :-— 
> 
* With the exception of Loriculus, of which one species (L. stigmatus) has 
straggled over into Ceiebes, all these types are confined to the Indian as distinct 
from the Australian region. In the same way a single species of Cacatua—a 
characteristic group of the Australian region—(C. philippinarum), is found in 
the Philippines, and a Tanygnathus, or probably two of this group (7. lucionensis 
and 7. sumatranus), the third species being peculiar to Celebes and Bouton. 
+ [have made some remarks on the exemplification of this law in the distri- 
bution of the Psittacide in the various West India Islands, in the ‘Annals and 
Magazine of Natural History ’ (1859), vol. iv. p. 224. 
t ‘ Ibis,’ 1860, p. 198. 
No. 431.—PROcEEDINGS OF THE ZOOLOGICAL SOCIETY. 
