NO. 2121. RACES OF THALA8SEUS BERGII—OBERHOLSER. 



525 



The specimens examined in the present connection measure as 

 follows : 



Measurements of specimens of Thalasseus bergii redirostris. 



THALASSEUS BERGII POLIOCERCUS (Gould). 



Sterna poliocerca Gould, Proc. Zool. Soc. Lond., 1837, p. 26 (Tasmania). 

 Sterna Novse-Hollandix Pucheran, Rev. et Mag. Zool., 1850, p. 545 (Cuvier MS.) 

 (Australia) (not Stephens). 



[Pelecanopus] nigripennis Bonaparte, Comptes Rend. Acad. Sci., vol. 42, 1856, 



p. 772 (nom. nov. pro Sterna novaehollandiae "Cuvier" [i. e., Pucheran]) 



(Australia^). 



Suhspecific characters. — Similar to Thalasseus hergii pelecanoides, but 

 averaging darker and sHghtly smaller. 



Measurements. — Wing, 285-350 (average, 329.7) mm.; tail, 131- 

 179 (156.9); exposed culmen, 5,5-66 (59.6); tarsus, 26.5-31 (27.9).'* 

 Wing, 326-353 (342. 1).^ 



Geographical distribution. — Coasts of New South Wales, Victoria, 

 and South AustraUa, south to Tasmania. 



Although this race is very close to Thalasseus hergii pelecanoides, 

 in both color and size, it is probably worth keeping separate on the 

 characters given above. It is to be noted that the present form is 

 darlcer, not lighter, than Thalasseus hergii pelecanoides, but is really 

 somewhat smaller, as writers have commonly credited it with being. 

 It is, however, paler than either Thalasseus hergii velox or Thalasseus 

 hergii cristatus, as well as much smaller than the first mentioned. 

 It is darker than Thalasseus hergii hergii, and, of course, decidedly 

 smaller. 



The name commonly applied to this race, when it is differentiated 

 from Thalasseus hergii hergii and Thalasseus hergii pelecanoides, is 

 Sterna hergii poliocerca; and the subspecific term poliocerca is appar- 

 ently correct, since Sterna novaehollandiae Stephens ® is, as 'Mr. G. M. 



' Used in measurements on p. 524. 



2 Type. 



'■' SincePelecanopus nigripennis Bonaparte is merely a substitute name for Sterna novaeTiollandiae Pucheran 

 it must have the same type-locality; and therefore Mr. Stresemann's designation of Tasmania as the type- 

 locality (Novit. Zool., vol. 21, Feb. 25, 1914, p. 58), can not stand. 



* Nine specimens, from Australia and Tasmania. 



^ Thirteen specimens, from southern Australia and Tasmania, measured by Stresemann. 



* Sterna Novx HoUandise Stephens, Shaw's Gen. Zool., vol. 13, pt. 1, 1826, p. 161 (Australia). 



