ZOOLOGY. 69 
1846, not a swallow of any description came under my 
observation, though I believe they were sufficiently common 
in Bermuda in September of the former year. 
When the swallow does visit the Bermudas on its southern 
migration, it makes its appearance with wonderful precision, 
- between the 9th and 16th of August, remaining only for a 
few days. Why these birds should persist in quitting those 
islands at a season of the year when the heat is tropical, 
and the supply of insect food abundant, is a query I will 
not attempt to answer. Were the periodical want of food, 
as some writers boldly assert, the principal cause of migra- 
tion, the swallow would not leave the Bermudas in the 
manner here stated, or return from the sunny regions of the 
south, where its natural food abounds at all seasons of the 
year. Twice only have a few swallows been observed on 
their vernal flight, in April and May. 
RUBY-THROATED HUMMING BirD (T7rochilus colubris). My 
endeavours to ascertain the truth of the tradition alluded to 
by Major Wedderburn, ended in disappointment. The bird 
seen by Mr. Darrell was described to me as greenish in 
colour, with the tail—the only part visible at times—tipped 
with white. I need not observe that this characteristic 
appertains to the female. 
VIRGINIAN Nicut Hawk (Chordeiles Virginianus). When 
this bird visits the Islands of Bermuda from the north, it 
invariably appears between the 20th of September and the 
11th of October, and on its verna! flight from the south, 
arrives with wonderful precision between the 25rd and 
30th of April. 
Gosse mentions this bird as present in Jamaica in the 
month of September, and again about the commencement 
