NO. 2121. RACES OF THALA8SEV8 BERGII—OBERHOLSER. 519 



THALASSEUS BERGII THALASSINUS (Stresemann). 



Sterna bergii thalassina Stresemann, Novit. Zool., vol. 21, February 25, 1914, 

 p. 57 (Goilon, Rodriguez Island). 



Subspecijic characters. — Similar to TJialasseus hergii hergii, but 

 decidedly smaller and somewhat lighter in color. 



Measurements.^ — Wing, 330-336 (average, 333) mm. 



GeograpMcal distribution. — The Seychelles Islands, south to the 

 islands of Aldabra and Rodriguez. 



Although the original series was small and we have nothing to 

 add, this race is apparently recognizable. It is, however, in color 

 very close to Thalasseus hergii rectirostris, and in size practically 

 identical with Thalasseus hergii cristatus; so that if we unite these 

 two 2 as Stresemann proposes, it would be difficult and somewhat 

 inadvisable to keep Thalasseus hergii thalassinus separate. 



THALASSEUS BERGH VELOX (Cretzschmar). 



Sterna velox Cretzschmar, Riippell's Atlas Reis. Nordl. Afrika, 1826, p. 21, 

 pi. 13 (coasts of the Red Sea). 



Subspecijic characters. — Similar to Thalasseus hergii hergii, but upper 

 parts decidedly darker. 



Measurements.^ — Wing, 356-380 (average, 368) mm. 



Geographical distribution. — Coasts of the Red Sea and Gulf of 

 Aden east to Sokotra Island; casually north in winter to the Sea of 

 Galilee, Palestine. 



This is one of the darkest races and needs comparison with only 

 Thalasseus hergii halceri, Thalasseus hergii edwardsi, and Thalasseus 

 hergii cristatus. 



THALASSEUS BERGH BAKERI Mathews. 



Thalasseus bergii halceri Mathews, Birds of Australia, vol. 2, pt. 3, September 

 20, 1912, p. 346 (Mekran coast of southeastern Persia and southwestern 

 Baluchistan). 



Subspecijic characters. — Similar to Thalasseus hergii velox, but larger, 

 and with darker upper parts. 



Measurements.'^ — Wing, 374-386 (average, 380.3) mm. 



Geographical distribution. — The Konkan coast of northwestern 

 India, northwest to the coasts of the Persian Gulf. 



This race appeal's to be easily recognizable by size alone, for it is 

 by considerable the largest form of the species. Although we have 

 exammed no specimens, there is no trouble at all in distinguishing it 

 from all the other dark subspecies, merely from the measurements 

 given by Mr. Stresemann.^ 



1 Three specimens, measured by Stresemann. 

 J Novit. Zool., vol. 21, Feb. 25, 1914, pp. 58^9. 

 3 Five specimens, measm-ed by Stresemann. 



* Six specimens, measured by Stresemann. 



* Novit. Zool., vol. 21, Feb. 25, 1914, pp. 57-58. 



