TOWNSEND AND WETMORE : THE BIRDS. 167 



structural characters separating the two that Mr. Mathews over- 

 looked. From the series available it seems that Scaeophaethon has 

 the operculum over the nostril broader and heavier, and barbs on the 

 shafts of the two elongate rectrices on either side greatly reduced in 

 length. This latter character is one by which Scaeophaethon may be 

 recognized at a glance. The black line at the side of the black shaft in 

 P. rubricmidus is misleading as it makes the shaft appear broad and 

 strong while in reality it is the same size as the shaft in P. aether eus. 

 When old and much worn the central rectrices of P. aethcreus become 

 narrowed and resemble those of Scaeophaethon but may be distin- 

 guished by their ragged appearance. As the small-billed P. americanus 

 also has a strong broad operculum the basis of differentiation falls 

 upon differences in the tail alone. These are assumed here to be only 

 subgeneric in value and the Red-tailed tropic-bird is kept in Phaethon. 



SULIDAE. 

 2. SuLA PiscATOR (Linne). 

 Pelecanus piscator Linne, Syst. nat., ed. 10, 1758, 1, p. 13-4. (Java Seas). 



Three specimens of this booby were collected at Tekokoto in the 

 Paumotu Islands; 26 October, 1899. None of these is in adult plumage 

 though all are one year old or more. One specimen, a male, has the 

 tail and head white, while the back and lesser wing coverts are hair- 

 brown. In the two remaining specimens the tips of the rectrices are 

 white and the rest of the plumage is dull. 



Mathews (Birds of Australia, 1915, 4, pt. 3, p. 216) states that 

 specimens of this booby from the Pacific Ocean are larger in every 

 dimension than those from the Atlantic region and that " the soft 

 parts seem to differ." For this reason he separates the Australian 

 bird under the subspecific name ruhripcs Gould. Concerning the 

 color of the soft parts information of value is not available, but com- 

 parison of a series of skins from Pacific and Atlantic Ocean localities 

 fails to substantiate the claim made as to dift'erence in size. So far 

 as measurements of wing, culmen, and tarsus go, specimens from the 

 Paumotu Islands are almost identical with birds collected by the 

 author on Desecheo Island, a small island lying between Porto Rico 

 and Santo Domingo in the West Indies. Careful study of a larger 



