PEALE'S EGRET HERON. 381 



need be mentioned) by which they may be at once distinguished from 

 the Ardeidce, consists in having the hind toe short, and inserted so high 

 up as to be raised from the ground except merely at the tip ; Avhile in 

 the Ardeidce it is long and bears with its whole length on the ground, 

 or nearly so. But as, according to the axiom of the great Linnd, the 

 character does not constitute the genus, even if the most general and 

 characteristic mark should fail us, it is still no reason why the group is 

 not natural which it has hitherto been believed to represent. A minute 

 peculiarity may furnish a most useful though artificial generic or specific 

 character, while an apparently important and evidently natural one may 

 be of no use for this purpose. In our system the family Ardeidce is 

 composed of nine genera, of which none is subdivided except Ardea 

 itself, which with Ciconia are all that are strictly typical. Besides the 

 more direct relations, this family is connected with the RalUdce by the 

 curious though anomalous Courlan, also allied to the Gruince by its feet, 

 as well as to the Scolopacidce. But to these the genus Eurypyga forms 

 a very strongly marked and still better passage. At the same time the 

 Platalea, which in its feet shows the transition to Phcenieopteridce, and 

 by its curiously flattened bill stands alone, is so similar in internal con- 

 formation, and especially the sternal apparatus, to the genus Ibis that 

 they ought in this respect to go together ; though Tantalus, one of the 

 Ibidce, is constructed rather upon the osseous plan of the Ardeidoi ! 

 Scopus, Anastomus, Canchroma, and even Dromas to a minor extent, 

 each and all exhibit striking anomalies in their bills, so that Ardea and 

 Ciconia are the only two typical genera with sharp-pointed bills of the 

 whole group. In order to comprehend all these forms of bills, it 

 becomes necessary to restrict greatly the physical characters of the 

 family, and we can merely observe that in the Ardeidce the bill, what- 

 ever be its form, is longer than the head, very robust, and almost always 

 sharp, with cutting edges. The neck is long. The feet long, and 

 always four-toed, the hind toe strong and well developed : the tarsus 

 is longer than the middle toe, and toes and nails both are also long. 

 The wings are of moderate length, and obtuse. The tail is never long, 

 nor otherwise remarkable, and consists of twelve, or only of ten 

 feathers. 



There is no marked external difference between the sexes, but the 

 young vary greatly from the adults, and do not gain their complete 

 plumage till their third year. 



In habits and internal conformation these birds are all much more 

 alike than in external. They have all a grave, deliberate, and well 

 poised gait : their flight is slow, though light and elevated, and they 

 stretch back their legs like sticks in flying, even more so than other 

 Waders. They are faithfully monogamous in their loves : their nests 

 are built with more art than those of aquatic birds generally, being 



