312 University of California Fuhlications in Zoology [Vol.13 



stout, ventral barbicels. The pcnnula of the proximals are fila- 

 mentous and take no part in the color production. 



In the breast of Fregata the barbules are slender and elongated, 

 with all the barbicels small and weak, but with no specialized 

 characters. 



(3) Sulidae 



The Sulidae, containing the genus Sula, or gannets, are almost 

 identical" with the cormorants and frigate birds in the minute struc- 

 ture of the remiges, except in the smaller size of the barbules, and 

 the slightly longer ventral teeth of the proximals of the inner vane 

 (pi. 19, figs. 16a, 16&), and the better developed series of ventral 

 barbicels of those of the outer vane, those representing the ventral 

 teeth being short, broad, and blunt, followed by a series of per- 

 fectly formed, hooked cilia, broad at their origin, and tapering 

 with the curve, as in the proximals of the outer vane of Aechnio 

 phorus (pi. 16, fig. 9d). 



The back and breast feathers have barbules very similar to the 

 less specialized ones of Phalacocorax and Fregata. The distals 

 (pi. 19, fig. 16c) are elongate, with short, stout booklets and a full 

 series of curved ventral cilia, the dorsal ones being less conspicuous. 

 The proximals (pi. 19, fig. 16d) are also long and slender with a 

 series of weak ventral cilia. Towards the tips of the barbs flexules 

 are developed very much as in Phaethon. (See below, and plate 19, 

 figures 19e and 19/). 



(4) Pelecanidae 



The pelicans, Pelecanidae, with the single genus Pelecanus, while 

 possessing the same essential characters of the barbules as do the 

 cormorants, frigate birds, and gannets, differ in a number of details. 

 In the remiges of Pelecanus erythrorhynchus the distal barbules 

 of the inner vane (pi. 19, fig. 17a-) are conspicuously short and 

 stout. The base is over 0.06 mm. wide, and only about 0.25 mm. 

 long, whereas if it had the same relative length as in Phalacocorax 

 it would be about 0.37 mm. long. The ventral teeth are very 

 broad and lobate, the booklets, about six in number, are relatively 

 slender and progressively longer, followed by a series of long, 

 slender ventral cilia, which lie close together on account of the 

 shortness of the cells. The dorsal barbicels resemble those found 

 in the more typical genera. In contrast to the distal barbicels, the 

 proximals (pi. 19, fig. 17&) have exceedingly long and slender bases, 

 being almost 0.9 mm. long and only about 0.06 mm. wide in the 



