BLUECAP—BOAT-BILL 45 
its place further to the south and westward ; and the third, of a 
lighter hue and with no chestnut, being the north-western form. 
The genus Sialia is one of those that are midway between the re- 
puted Families Sylviidx# (WARBLER) and Turdidx (THRUSH), and with 
Monticola and some others shew how hard it is to maintain any 
valid distinction between them. The Bluebirds of North America 
breed in holes of trees, and seem all to lay pale blue spotless eggs. 
In Western India, Ceylon, and Burma, the name Bluebird is equally 
well bestowed on the Jrena puella of modern ornithologists, which 
is commonly referred to the chaotic groups Jimeliidx or Crateropo- 
didx (Oates, Fauna of British India, Birds, 1. pp. 239, 240), and has 
several representatives in the Indian Region (Jerdon, B. India, ii. 
p. 106); but the precise place of the genus must be regarded as 
uncertain. According to Mr. Layard (Bb. S. Afr. p. 365), in the 
seas of the Cape of Good Hope, the name is applied to a wholly 
different kind of bird, Diomedea fuliginosa (ALBATROS). 
BLUECAP, a common name of the Blue Titmouse Parus 
cxeruleus. 
BLUETHROAT, the English name by which the beautiful JJota- 
cilla suecica of Linneeus is now generally known. By some systematists 
it has been referred to the genus Futicilla (REDSTART) or to Lrithacus 
(REDBREAST), and by others. regarded as the type of a distinct genus 
Cyanecula—the last view being perhaps justifiable. There are two, 
if not three, forms of Bluethroat in which the male is quite distin- 
guishable :—(1) the true C. suecica, with a bright bay spot in the 
middle of its clear blue throat, breeding in Scandinavia, Northern 
Russia, and Siberia, and wintering in? vgasinia and India, though 
rarely appearing in the intermediate countries, to the wonder of all 
who have studied the mystery of the migration of birds ; next there 
is (2) C. leucocyanea, with a white instead of a red gular spot, a 
more western form, ranging from Barbary to Germany and Holland ; 
and lastly (3) C. wolfi, thought by some authorities (and not without 
reason) to be but an accidental variety of the preceding (2), with 
its throat wholly blue,—a form of comparatively rare occurrence. 
The first of these is a not unfrequent, though very irregular visitant 
to England, while the second has appeared there but seldom, and 
the third never, so far as is known. The affinity of the Bluethroat 
to the Redstart is undeniable ; but it is not much further removed 
from the NIGHTINGALE, and forms a member of that group which 
connects the so-called Families Sylviide (WARBLER) and Turdidx 
(THRUSH). 
BOAT-BILL, the Cancroma cochlearia of most ornithologists, a 
native of Tropical America, and the only species of its genus. It 
seems to be merely a Night-Hrron (Nycticorax) with an exaggerated 
bill, so much widened as to suggest its English name, and its habits, 
