NATURAL SCIENCES OF PHILADELPHIA. 287 



breed in the fissures of the rocks, in places in which, though I have often 

 seen them enter, I was unable to follow from their narrowness. The eggs are 

 pure white. 



14. Tachoknis phojnicobia. We have here, with the Palm Swift, an in- 

 stance of a total change from natural habits induced by adventitious circum- 

 stances. Previous to 1854, the habitat of the Palm Swift was altogether 

 confined to the palm-trees, in this district (St. Catharine), and to the cocoa- 

 nut palms near the coast at Wreck Bay, Healthshire, Port Henderson and 

 Dawkins Pen, at Passage Fort. In that year a colony of them established 

 themselves on two cocoanut palms in Spanish Town, one near the centre of 

 the town, the other at the northeast corner, and there they remained until, 

 in 1857, the palm at the northeast was taken down and the other divested of 

 the lower fronds, and the Swifts turned adrift. They were then for the first 

 time observed flitting about the lower pinzzas of the House of Assembly, the 

 upper part of this building having been previously occupied by the H.fulva. 

 In a short time these prior occupants were driven out, and a considerable 

 colony of Palm Swifts now occupy the lower colonade in front of the ground- 

 story used as public oflices, where they build on the tops of the end walls, 

 or at the angles formed by the beams and joists. None resort to the upper 

 piazza ; but they pertinaciously drive away the H. fulva on every attempt 

 they make to effect a lodgment. Small colonies of the Palm Swifts last 

 year (1862) again returned to the palm in the centre of the town, but 

 the large colony still retained its position in the buildings. The nests are here 

 built in clusters, without the elaboration found on those in the palm spathes. 

 Each nest contains two or three long-oval, pellucid white eggs 10-16ths to 

 12-1 6ths by 7-16ths. Before the eggs are blown, the yolk gives them a pale 

 amber tint. Two small colonies of the H.fulva have this year (1863) effected 

 a lodgment in the upper piazza of the buildings, but they have an unquiet 

 time of it, the Palm Swifts keeping up a continuous warfare with them. 



15. Cypselus niger. This, like the preceding species, is rarely seen, ex- 

 cept in early dawn, or in dull, cloudy weather, or after rain in the afternoon. 

 I have sometimes procured specimens from Healthshire and the St. Catharine 

 Hills. The only place of their actual resort I know, is a cave on the lower 

 St. Catharine's Hills, near the Ferry, where they dwell in the narrow, deep 

 galleries and fissures of the limestone rocks. 



TYRANNIDJE. 



48. Tyrannus griseus. (J". Dominicensis, Gosse.) The number of Petch- 

 aries departing from, or remaining in, the island seems to depend in a great 

 measure on the supply of insect-food consequent on a dry or wet summer. 

 There is some confusion in Mr. Gosse's first quotation from Mr. Hill's notes, 

 the emigration of the Petchary occurring in October, and the immigration 

 in early spring. The word migratory in the first paragraph of the quotation 

 evidently refers to those birds forming the band of migrants preparing to de- 

 part from, and not to their actual departure from or return to, the island. 

 The facts as I have observed them are, that during the last few days in Au- 

 gust or the first in September, the Petcharies quit their usual haunts and 

 resort to the pastures, savannahs and adjacent hills and valleys along the 

 coast, both on the north and south sides of the island. During the day they 

 keep to the woodlands, but an hour or two before sunset they congregate on 

 the tall trees around the ponds about the pastures and savannahs, and in the 

 vicinity of river-courses and mangrove swamps, wherever their insect-food is 

 most abundant, to take their evening meal before roosting for the night ; and 

 there, perched several in rows on the most elevated, dry branches, they dart 

 about uttering their peculiar cry and capturing insects, always returning to 

 their perch to devour their prey. In a few days they become exceedingly fat, 



1863.] 



