202 BULLETIN 121, UNITED STATES NATIONAL MUSEUM. 



about the borders, of a "prickly-pear" cactus {Oinuitia) and sea laveuder 

 (Tournefortia gnaphalodes) . Where sufficient soil has accumulated the remain- 

 der of the island supports a growth of coarse grasses, sparse on the higher and 

 rockier portions, more luxuriant in tlie lower portions, particularly about the 

 margins of a small salt pond, the size of which was dependent upon conditions 

 of tide and wind. There is no fresh water on the cay. 



He remained on the island from April 9 to 11, 1907, and wrote a 

 full account of his observations, from which I quote in part : 



A partial census of eggs and young led to the conclusion that there were 

 about 1,500 pairs of boobies nesting on Cay Verde. Tliey were distributed in 

 several groups, where the comparatively level surface and sandy soil furnished 

 favorable nesting conditions. In most instances the young were covered with 

 down, with the brown second plumage more or less evident in wings and tail. 

 A few birds of the year were already awing, and several nests contained fresh 

 eggs. For the greater number of birds, however, the nesting season, as Bryant 

 has stated, evidently begins in February. 



The booby's nests on Cay Verde were usually slight hollows in the ground, 

 with often a scanty lining or rim of dried grasses, but in some instances even 

 this humble preparation for housekeeping was lacking, and the eggs were laid 

 without pretence of nest. 



About 98 per cent of the boobies nesting on Cay Verde had young, some of 

 which were newly hatched, while a few were on the wing, but the largest 

 number were beginning to acquire flight feathers. Of the nests, 35 contained 

 eggs, of which 21 held 2 eggs, while in 14 there was but 1, but possjbly in some, 

 if not most, of these another egg w'ould have been laid. As a rule, therefore, 

 there were 2 eggs, this confirming previously recorded observations on the 

 nesting habits of this species. On the other hand, 2 young were the exception. 

 Of 740 nests counted by Doctor Mayer on the east side of the cay, only 2 con- 

 tained young, and both pairs were well grown and approximately the same size. 



Examination of the eggs contained in sets of two showed that either there 

 was a marked difference in the development of the embryos or that one or both 

 eggs were infertile. For example, of 13 nests containing 2 eggs, in 3 nest.-i 

 both were bad ; in 10 both were good ; but with every good pair there was 

 about a week's difference in the age of the embryo. In 6 nests, each contain- 

 ing one young and one egg, 5 of the eggs were decomposed. 



With those bobbies which lay 2 eggs, apparently a week intervenes between 

 the laying of the first and second egg, and to this unusual irregularity, iu 

 connection with the high percentage of infertility, we attribute the discrep- 

 ancy between the number of eggs laid and the number of young reared. 



Dr. Alexander Wetmore has contributed the following notes on 

 another interesting colony of this species : 



Off the west coast of Porto Rico, seven leagues from the port of Aguadilla, 

 lies the small island of Desecheo, hot and dry for a large part of the year, but 

 swept occasionally by tempestuous downpours of rain. The island is little 

 more than an isolated rock rising from the restless waters of Mona passage 

 with its treacherous changing currents, profound depths all about cutting it 

 off from other land connection. In shape it is roughly an ellipse a mile and 

 a half long and three-fourths of a mile wide with abrupt rocky shores and 

 steep slopes rising into two pointed hills, the highest about three hundred feet 

 above the sea. Three or four small indentations boast a rough gravelly beach 

 where with care a landing can be made in the surf and behind these are small 



