492 bulletin: museum of comparative zoology 



colymbidae. 

 12. PoDiCEPS PELZELNi Hartlaub. 



Five specimens, four adults in non-breeding plumage and one young 

 in down, Sahabe River, Miandrivazo, and Mahabo, June, July, and 

 September. 



These skins have been carefully compared by Dr. Richmond with 

 the series of P. capensis in the U. S. N. M. The four adults certainly 

 are P. pelzclni which can be separated from P. capensis by the angle 

 of the gonys being more lengthened, and the under mandible turning 

 up rather less abruptly at the tip. There is also a tendency to a 

 dusky spot near the tip of the outer secondaries in P. pelzelni. 



Laridae. 

 13. Hydrochelidon leucopareia delalandii Mathews. 



Four adults, both sexes, all in winter plumage, southern end of 

 Lake Alaotra, September 25. 



I follow Mathews in recognizing a South African form, to which I 

 refer our birds, not having sufficient material to decide the question 

 as to the recognition of a subspecific form. 



14. Sterna bengalensis arabicus (Mathews). 



One male (adult in winter plumage?) mouth of the Onilahy River, 

 August 4. 



In this instance, also, I simply follow Mathews. 



15. Larus dominicanus Lichtenstein. 



Two adult males, Ambola, southwest coast, August 7, and Nosy 

 Asatra to Beheloka, August 6. 



Mathews and Iredale, in their Reference list of the birds of New 

 Zealand (Ibis, 1913, 10, p. 248) use the name Larus dominicanus 

 antipodus (Bruch) for the New Zealand bird without stating how it 

 differs from the South American true L. dominicanus. I have care- 

 fully compared a number of specimens from each of the following 

 localities : — southern South America, South Africa, and New Zea- 

 land and can find no tangible differences by which to separate them. 

 I therefore consider them as belonging to one and the same subspecies. 



