that connect the Orders and Families of Birds. 477 
the extremes of that varied structure. With almost equal certainty 
they reduce to the regularity of law the otherwise anomalous for- 
mation of the Tachypetes, explaining its connexion with Hirundo, 
and accounting for the weak and feathered legs, the forked tail, 
the expansive wing, the powers of the long-suspended flight, 
which give each bird the command over the element in which 
they range in common. But I must restrain myself, or I should be 
involved in an endiess discussion of*similar coincidences. It is 
sufficient to have suggested the principles that regulate such ana- 
logies, and the intelligent ornithologist will himself discern the 
numberless and beautiful inferences that result from them. Pro- 
ceed we now in order to the next succeeding department of the 
class. | 
Ord. Ill. RASORES. 
The two typical orders which have already come before us exhi- 
bit the most generally perfect structure that is found among birds, 
and consequently indicate the most extensive powers, and the 
widest sphere of action. The strength and perfect developement 
of their wings confer on them the faculty of locomotion to the 
fullest extent; while the structure of their foot affords them equal 
facility in grasping their prey, in walking, climbing, and perch- 
ing. 'They thus extend their dominion over nature almost 
without any apparent limits. The different elements seem alike 
subservient to their purposes: on land, they form their habita- 
tions and obtain their food in the forest, on the plain, and the 
mountain; they pursue their prey through the tracts of air, and 
are not debarred even from the waters. Pursuing the same line 
of inquiry among the aberrant groups of the class, we may 
observe their powers which depend on conformation becoming 
more circumscribed, and their sphere of life brought conse- 
392 quently 
