312 University of California Publications in Zoology  {Vor.138 
stout, ventral barbicels. The pennula 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 
(pl. 19, figs. 16a, 160), 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 Aechmo- 
phorus (pl. 16, fig. 9d). 
The back and breast feathers have barbules very similar to the 
less specialized ones of Phalacocoraz and Fregata. The distals 
(pl. 19, fig. 16c) are elongate, with short, stout hooklets and a full 
series of curved ventral cilia, the dorsal ones being less conspicuous. 
The proximals (pl. 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 Phaéthon. (See below, and plate 19, 
figures 19¢ and 19f). 
(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 (pl. 19, fig. 17@) 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 hooklets, 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 (pl. 19, fig. 17b) have exceedingly long and slender bases, 
being almost 0.9 mm. long and only about 0.06 mm. wide in the 
