16, 4 McGregor: Some Features of the Philippine Ornis 415 
shown that Balabac is closely related to Palawan in regard to 
its birds. 
Worcester *° has published a very detailed review of Steere’s 
work, taking advantage of much information in regard to dis- 
tribution that was not available to Steere, notably the results 
of the Menage expedition and of Whitehead’s numerous collec- 
tions from the highlands. 
Since Worcester and Burns“ published their list a great 
deal of detailed work has been done on the distribution of the 
lowland species. Most of this has been published by Grant, 
W. E. Clarke, Worcester, Mearns, and McGregor. 
In 1906 Worcester *? republished his conclusions as to the 
divisions of the Islands that can be recognized, these conclusions 
being somewhat modified and extended by the work on distri- 
bution of Philippine birds that had been done since 1900. . 
It would be difficult to state the matter in clearer or more 
concise form than Worcester has done; and I shall quote from 
him in full, adding a few remarks of my own in square brackets. 
Worcester considers that the Philippine Islands may be divided 
into zodlogically distinct groups as follows: 
(1) The Palawan group, consisting of Palawan and the small islands 
adjacent to it, Balabac, Cagayan Sulu, and the Cuyos and Calamianes 
Islands. The birds of this group show a very strong Bornean element. 
The line of demarcation between the Philippines, zodlogically speaking, 
and the Palawan Islands passes between Sibutu and the coast of Borneo 
and extends thence northward through the Sulu Sea east of the Cuyos 
group and through Mindoro Strait. [I do not include Cagayan Sulu in 
the Palawan group. The identification of specimens of Pycnonotus plu- 
mosus Blyth from Cagayan Sulu “ adds to the previously existing evidence 
of the Bornean affinity of this island.] 
(2) The central Philippines, comprising the Islands of Negros, Panay, 
[Bantayan,] “ Guimaras, Masbate, and Ticao. They form a well-defined 
natural group, although in the case of Masbate and Ticao there are indica- 
tions of immigration from Luzon. [Marilison and Batbatan, off the coast 
of Antique Province, Panay, have yielded no species that would indicate 
the faunal relationships of these small islands.] * 
(3) Mindoro and some of the islands immediately adjacent to it, includ- 
ing Semerara and doubtless also Ylin. [A few birds have been recorded 
” Proc. U. S. Nat. Mus. 20 (1898) 567-617. 
"Op. cit. 551-564. 
“In McGregor, R. C., and Worcester, D. C., A Hand-list of Birds of 
the Philippine Islands. Bureau of Government Laboratories, Manila 36 
(1906) 5. 
“McGregor, R. C., Philip. Journ. Sci. § D 11 (1916) 274. 
“See McGregor, R. C., Philip. Journ. Sci. § A 2 (1907) 310. 
“Bureau of Science collections of 1918; results unpublished. 
