480 Recent Literature. [july 



types or genes of terns, one laying green eggs and the other brown. This 

 would, however, necessitate mating always within the gens or the trans- 

 mission of the egg coloring mechanism through the female only. The 

 former is hardly conceivable while the latter is contrary to the experience 

 of breeders that female characters are transmitted through the males. 

 This theory too would require some Cuckoo-like females laying in the 

 nests of other individuals to produce the varied sets of green and brown 

 eggs in the same nests, which for various reasons does not seem credible. 

 The most likely theory seems to be that any female tern may lay either 

 a green or a brown egg but that with the physiological exhaustion inci- 

 dent to successive egg laying the nature of the pigment of the egg laying 

 glands changes. This would explain the undoubted fact shown by the 

 tables that the number of green eggs increases with the number in the 

 clutch, there being 74 brown to 63 green in clutches of a single egg; 153 

 brown to 203 green in clutches of two; and 216 brown to 393 green in 

 clutches of three. There are a number of admirable photographic plates 

 showing the birds and nests and a color plate illustrating extreme phases 

 of egg coloration. The paper is well worth careful study by those in- 

 terested in the theories upon which it touches or in mathematical methods 

 in research — W. S. 



Report of the National Zoological Park. 2 — In his annual report as 

 superintendent of the National Zoo, Mr. Hollister presents a number of 

 interesting statistics. The number of species of birds in the collection 

 is 190, exactly the same as last year, although the individuals are slightly 

 more numerous. The death of the female Trumpeter Swan which had 

 just been successfully mated with the male loaned by Mr. R. Magoon 

 Barnes was a calamity, and until other specimens of this disappearing 

 species can be secured will check any attempt to perpetuate it. Several 

 birds, long residents of the garden, also died during the year, including a 

 Crowned Hawk Eagle (Spizaetus coronatus), a resident for nearly 18 years; 

 two tree clucks (Dendrocygna arcuata) which had lived there for 15 years 

 and a Snowy Egret for eleven years. — W. S. 



Ornithology of the Princeton Patagonian Expedition. — Part IV 

 of this sumptuous work appeared in July 8, 1915. Like the preceding 

 parts it is the work of the late Dr. R. Bowdler Sharpe and W. E. D. Scott, 

 their manuscripts having been published with only slight changes in no- 

 menclature and minor details. The editing has been done by Dr. Witmer 

 Stone who will prepare the text for the remainder of the work as the manu- 

 scripts of the late authors were only completed to the end of the Accipi- 

 triformes. The present part covers pages 505-718, and includes the Pele- 

 caniformes, Accipitriformes and Strigiformes. 



2 Report of the Superintendent of the National Zoological Park for the Fiscal 

 Year ending June 30, 1919. Ann. Rep. Smithson. Inst, for 1919, pp. 68-81, 1920. 



