REMARKS ON THE BITTERNS. 
73 
there is no indication even of a passage into other forms; and the essential 
characters of the common Grey Heron of this country will apply to the whole 
series. The immediately superior group comprises four such distinct, though 
nearly allied, types, which, according to my notions, should constitute as many 
separate families: of these the Heron, Stork, Spoonbill, and Ibis genera are 
respectively typical; and each is distinguishable by anatomical, equally with 
external, characters. I am far from being satisfied that the Courlan ( Aramus ) 
appertains to the same major division; and deem it the wisest plan to refrain 
from making any remarks on this singular bird till I know something of its 
rudimental anatomy. 
The whole of the above minor groups, together, compose the Ardeidce of the 
Quinary systematists, and the Grallatores Robustirostres of an arrangement 
which I am preparing for publication. They are distinguished from all other 
Grallatores by coming into the world helpless and blind, requiring to have food 
placed in their mouths. Of moping sedentary habits, they commonly remain a 
long while fixed in the same position: and feed exclusively, or very nearly so, 
on animal matter, chiefly on small-sized Vertebrata , though, in short, on what¬ 
ever moves that is not too large for being swallowed. The majority perch, and 
even nestle on lofty trees, frequently several species together, in numerous 
societies; and, excepting the Spoonbills, I believe they all lay spotless eggs, of 
which the yolk is disproportionately small, and the shell thin. The period of 
incubation is comparatively brief, which accords with the helpless condition in 
which the young are excluded. A large proportion of them do not attain 
maturity until they are two years old; continuing solitarily dispersed in marshy 
districts during the first season of propagation. The common British Heron 
may again be selected as the general standard of the entire division. 
But it is with the first of the four minor groups that we are now more parti¬ 
cularly concerned; and I shall henceforward speak of it under the term Ardeidce , 
from which it will be understood that the Storks, Spoonbills, and Ibises, with 
their subordinate genera, are excluded. All four possess a large and membranous 
stomach, and very wide gullet; intestines narrow, and of considerable length; 
the Spoonbills have no caeca; the Storks and Ibises two caecal appendages of 
small size, most developed in the latter; and the Ardeidce , in every instance, a 
single minute caecum. The last-named have also the ordinary pair of sterno¬ 
tracheal muscles to the inferior larynx; of which the Spoonbills, Storks, and I 
suspect the Ibises, are devoid, whence these birds are necessarily destitute of 
voice, which is the more extraordinary in the instance of the European Spoon¬ 
bill, the trachea of which species undergoes a peculiar convolution. In the 
Ardeidce , the inner edge of the middle claw is constantly pectinated ; no trace of 
this structure occurs among the Storks and Spoonbills, and only a slight indica- 
