ZOOLOGY. 485 



Zoofaloin affords a spectrum '' with two absorption-bands which how- 

 ever are not those of Turaciu." 



Tlie attempts made "to extract blue, violet, and green pigments 

 from feathers so colored have as yet been unsuccessful; and these 

 colors may therefore depend upon optical, and not chemical, causes." 

 (Ibis, (4,)V. 602-603.) 



Number of American birds.* 



In 1859 was published a catalogue of the known North American birds 

 north of Mexico, prepared by Professor S. F. Baird, which for many 

 years afterward was the standard authority for the nomenclature and 

 arrangement of the species. But the numerous additions that have 

 been made from time to time, as well as the investigations upon the af- 

 finities of the forms, have necessitated a new arrangement. In 1873 a 

 check list of the species was published by Dr. Elliott Cones, which incor- 

 porated the forms up to that time added to the fauna. Discovery still 

 progressed, however, and during the past year a new catalogue of all 

 the species was prepared by Mr. Robert Eidgway, and has been issued 

 by the Smithsonian Institution, as a "Bulletin of the United States Na- 

 tional Museum," and a comparison of it with that of 1858 is instructive 

 hi its illustration of the tendencies of ornithologists at the two periods. 

 The catalogue of 1859 bears the impress of the influence of Professor 

 Agassiz and Bonaparte in the excessive diflerentiation of species. Since 

 that period the comparison of birds obtained from the various portions of 

 our wide domain has shown that nominal species concerning which there 

 existed no doubt in the early period are connected by intermediate forms 

 obtained from intervening stations, and consequently a number of 

 old species have been associated together as mere varieties or "sub- 

 species" of more comprehensive species. On the other hand, the same 

 system of comparison has compelled ornithologists to recognize the fre- 

 quent existence of such differences between forms found at widely re- 

 mote regions as to warrant the introduction of the categoi-y of "sub- 

 species " or varieties which hav^e received trinomial names. Thus we 

 have many old species now combined together as forms of others but with 

 varietal differentiations ; in other words, the fact that while most of the 

 individuals are separated into two or more types of differentiation as 

 distinct forms is indicated by then" recognition as varieties, nevertheless 

 intervening forms occur which forbid their rank as fully developed 

 species. 



Comparing the catalogues of 1859 and 1881, the number of avowed 

 species in the former is 738, and in the latter 764, but the actual num- 

 ber of names, that is, forms more or less distinct, including species and 

 subspecies, was in the catalogue of 1859 764, but in 1881 924 are rec- 



* Ridgway (Robert). Nomenclature of North American Birds, chiefly contained in 

 the United States National Mnseiun. Washington, Government Printlng-Office, 1881. 

 (Bulletin of the United States National Museum, No. 21.) 



