Supposed occurrence of Hirundo bicolor in England. 131 
« British-bird”’ students who find in these alien immigrants a great 
cause of perplexity. To whatever country we go, we are, perhaps 
before we have well ascertained the number of the dond fide species, 
puzzled by some wanderer turning up exactly where he was least 
wanted. In my own opinion, the ornithologist must accept his 
position with all its responsibilities ; he chooses to study a class of 
beings, some of whom, for all sublunary purposes at least, are blest 
with almost infinite powers of locomotion. He must therefore not 
complain if in the course of a morning’s walk here in England, an 
Australian Swift flies in his face, or he picks up a dead Crossbill of a 
Transatlantic species ; and he must invoke no Deus ex machina in the 
shape of an auxiliary-screw clipper or a careless. aviary-keeper to 
account for the incident. Facts like these hardly admit of a doubt, 
and force themselves day by day more and more upon the notice of 
the thoughtful naturalist. For some time, indeed, European orni- 
thologists have been accustomed to regard the properly authenticated 
appearance of an exotic species, which there may be good reason to 
suppose to have reached our shores without intentional human aid, 
as sufficient ground for including it in the list of our birds. But as 
observers have of late so largely increased, so have these occurrences 
been more frequently noticed ; and it seems absolutely necessary to 
prescribe some limit to prevent our really native species from being 
outnumbered by these foreigners. The difficulty is to know where 
to draw the line; and to this pomt I would invite the careful con- 
sideration of naturalists. It may be all very well to call Thalassi- 
droma Wilsoni and Mergus cucullatus European birds ; but because 
a single individual of Regulus calendulus or Dendreeca virens has 
reached the Old World, it is absurd to include either of those species 
in its Fauna. I cite these instances because they are all from that 
continent whence most of our occasional visitants arrive—so much 
- so, that one is almost driven to the conclusion that there is no primd 
facie reason why examples of the greater number of birds of Eastern 
North America should not, favente zephyro (the prevailing strong 
wind in Western Europe), make their appearance on our shores in 
course of time. Then, on the other hand, the last two additions to 
the list of so-called “‘ British birds” have been from the opposite 
quarter. Are Syrrhaptes paradoxus and Xema ichthyaétus to take 
their places in the books elucidating British Ornithology by the side 
of the Red Grouse and the Peewit Gull? It appears to me that we 
gain nothing by deferring a decision on the subject, and I trust that 
these remarks will not be deemed unnecessary by those who are 
competent to deal with the matter. 
Elveden, 28 February, 1860. 
Description or A New Genus or BoIp# DISCOVERED BY 
Mr. Bates oN THE Upper Amazon. By Dr. J. E. Gray. 
Fam. Borpz. 
CHRYSENIS, 0. g. 
Head rather large, rather depressed, covered with scales, the front 
half covered with small symmetrical shields, as follows :—two pair 
. * 
