72 
REMARKS ON THE BITTERNS. 
By Edward Blyth. 
The comprehensive genus Ardea , as defined by Temminck, and adopted by 
Mr. Jenyns in his Manual of British Vertebrate Animals , is exceeding difficult 
to subdivide into minor groups, corresponding to the genera of other recent 
systematists. To confine our attention to the few species admitted into the 
British Fauna, the distribution of these into Herons, Bitterns, and Nightherons, 
may appear sufficiently cogent, as the typical forms are mutually very distinct ; 
but numerous exotic species connect these primary modifications of the same 
type so intricately, that although in the present state of Ornithology their 
separate recognition is absolutely requisite, it is impracticable to furnish respec¬ 
tive definitions that should include all the species, and the only available method 
of distinguishing them systematically is to indicate the prevalent distinctions of 
the more characteristic species, the dividing lines—of whatever value we choose 
to make the subordinate groups—being utterly arbitrary. Indeed, it is hardly 
necessary to seek beyond the British (or, more properly speaking, British-killed) 
species, for exemplification of the futility of attempting dichotomous separation. 
The Purple Heron, though otherwise a typical Ardea , has the toes and long 
claws of a Bittern; as has also the Buff-backed Heron or Egret ( Ardea-egretta 
russata), the short and comparatively weak bill of which, I have little doubt, 
will sooner or later induce somebody to make a separate division of it. Boje 
has already indicated A. ralloides , Auct., and some allied species, under the 
designation Buphus , and the Prince of Musignano has distinguished the tiny 
Dwarf-bitterns by the term Ardeola; the former having been variously posited, 
by different writers, as Herons or Bitterns; and the latter, also, grouped with 
the Bitterns by Mr. Selby, whereas Mr. Jenyns deems^them to be more imme¬ 
diately related to the true Ardece. Again, the Cayenne Nightheron (Yellow- 
crowned Heron of Wilson) deviates considerably from the type of Nycticorax , 
approximating the Boatbills ( Cancroma ); which latter are physiologically as 
closely allied to the rest of the group as are either of the previously specified 
divisions. Save the American and European Bitterns, therefore, and the greater 
and smaller European white Egrets, not two of the various species which have 
occurred in Britain are subgenerically altogether identical. Still it is only when 
a numerous suite of foreign species are placed in juxta-position, that the nullity 
of what many consider to be satisfactory separations becomes palpably apparent. 
On the other hand, however, the entire group (comprising the Boatbills, of 
which the beak, as stated by Cuvier, is simply that of a Heron or Bittern, very 
much flattened and inflated) is as thoroughly distinct from all other groups, even 
the most allied—which is that of the Storks and Adjutants—as can well be; 
