RENDAHL, BIRDS FROM THE PEARL ISLANDS. 7 



allied to that of the adjacent main. This is also the case as 

 already was shown by Messrs. Thayer and Bångs. 



The Pearl Islands present, however, a much smaller and 

 less varied space for life than the Panama mainland, and in 

 consequence a great many of the mainland birds are absent 

 from the islands. Of the following families no species have 

 been found there: 



Podicipedidae Cancromidae Tytonidae Motacillidae 



Parridae Plotidae Cypselidae Cinclidae 



Oedicnemidae. Hhamphastidae Bendrocolaptidae 



Eurypygide Capifonidae Cotingidae 



Heliornitidae Bucconidae Pijyridae 



Odontoplioridae Galhulidae. Oxyruncidae 



Plataleidae Momotidae Corvidae 



Ciconiidae Nyctihiidae Ampelidae. 



About the communication between birds from the islands 

 and those from the mainland we have but little knowledge, 

 Mr. Bångs states that Mr. Brown on several different occa- 

 sions saw specimens of Chlorostilbon assimilis flying from the 

 mainland straight for the Archipelago. However this may 

 be, some species of the islands show racial differences from 

 their allies in the main. Of the sixty-three species inhabiting 

 the islands no less than ten have been described as endemic 

 species or subspecies by Messrs. Bångs, Oberholser, and 

 Thayer, viz.: — 



Butorides virescens margaritopJiilus. 

 Phaétliornis antliopMliis hyaUnus. 

 Centicnis seductus. 

 Elaenia chlriquensis sordidata. 

 Microphias grisea alticincta. 

 Thryophilus galbraithii conditus. 

 Vireosylva flavoviridis insulaniis. 

 Coereba cerioclunis. 

 Bampliocelus dimidiatus limatus. 

 Tanagra cana dilucida. 



Such a rich endemical bird fauna is really to be indica- 

 ted as remarkable. About the distinctness of some of these 

 endemic forms my researches, however, as followed up in the 

 following list of species, have caused me to be very doubtful. 

 One of them Tanagra cana dilucida cannot be maintained as 

 subspecies, being identical with T. c. diaconus of the main, to 

 which it also was referred by Count Berlepsch. Of Butorides 



