484 MR. W. B. ALEXANDER ON THE 



OSTKACIOHTID*. 



Anoplocapros lenticularis, Rich. 



Tethocontidj. 

 Spheroides pleurogramma, Regan. Blow-fisli 



Pediculati. Bateachidje. 



Cokyzichthys diemensis (Rich.). Recorded from the Abrolhos by 

 Richardson. There is a specimen in the W.A. Museum. 



SUMMARY. 



The marine fauna of the Abrolhos Islands was stated by Saville Kent (14) 

 to be a remarkable mixture of temperate and tropical forms. Apart from 

 the corals, which are outside the scope of the present paper, he specially 

 instanced the fish, many of which he stated were common to the Abrolhos 

 and the Barrier Reef and Torres Straits. It will be worthwhile therefore to 

 examine how far his statement is borne out by the distribution of the marine 

 vertebrates recorded in the present paper. 



Sea-birds. — The 36 species of sea-birds which occur on the group may be 

 divided into the following groups. Summer visitors— 11 : wading birds from 

 the Northern Hemisphere, all of which travel farther down the coast than 

 the Abrolhos. Winter visitors — 2 : the Yellow-nosed Albatross has been 

 recorded from as far norlh as Point Cloates, the Giant Petrel has not been 

 met with north of the Abrolhos. The breeding-places of both are unknown, 

 but are doubtless much farther south. Other southern sea-birds probably 

 occur about the Abrolhos in winter, but almost all the collecting done on the 

 group has been carried out in summer. Casual visitor — 1: the Black Swan. 



The remaining 22 species all breed on the group. Of these 12 are forms 

 found breeding in other localities along the west coast, both north and south 

 of the Abrolhos. Four are not known to breed farther north ihan the 

 Abrolhos, viz., Pelagodroma marina dulcice, Puffinus assimilis lunneyi, Sternula 

 nereis horni, and Gabianus pacificus georgii. Five are not known to breed 

 farther south than the Abrolhos, viz., Sterna do ug alii gracilis, Onyclioprion 

 fuscata serrata, Anous stolidus gilberti, Ihematopus ostralegus picatus, and 

 Scceophaethou rubricauda ivestralis. The Abrolhos form of the Lesser Noddy, 

 Megalopterus tenuirostris melanops, is not known to breed anywhere else, 

 but as its near ally M. tenuirostris tenuirostris breeds in the Seychelles it 

 may be accounted a northern form. 



Judging from the sea-birds, therefore, we may conclude that there is a 

 distinct admixture of northern and southern forms, and the three most 

 plentiful species — the Sooty Tern, Noddy, and Lesser Noddy — are all forms 

 which arc specially characteristic of tropical islands. 



