TRANSITIONS OF OliGANIG BEINGS. IfiO 



this same woodpecker, as Mr. Hudson states, frequents 

 trees, and bores boles in tbe trunk for its nest. 1 may 

 mention as anotber illustration of tbe varied babits of tbis 

 genus, tbat a Mexican Colaptes lias been described by De 

 Saussure as boring boles into bard wood in order to lay up a 

 store of acorns. 



Petrels are tbe most aerial and oceanic of birds, but, 

 m tbe quiet sounds of Tierra del Fuego, tbe Puffinuria 

 berardi, in its general babits, in its astonisbing power of 

 diving, in its manner of swimming and of flying wben 

 made to take fligbt, would be mistaken by any one 

 for an auk or a grebe; nevertbeless it is essentially a 

 petrel, but witb many parts of its organization pro- 

 foundly modified in relation to its new babits of life; 

 fs^bereas tbe woodpecker of La Plata bas bad its structure 

 only sligbtly modified. In tbe case of tbe water-ouzel, 

 tbe acutest observer, by examining its dead body, would 

 never bave suspected its sub-aquatic babits; yet tbis bird, 

 wbicb is allied to tbe tbrusb family, subsists by diving — 

 using its wings under water, and grasping stones witb its 

 feet. All tbe members of tbe great order of Hymenopter- 

 ous insects are terrestrial, excepting tbe genus Procto- 

 trupes, wbicb Sir Jobn Lubbock bas discovered to be 

 acquatic in its babits; it often enters tbe water and dives 

 about by tbe use not of its legs but of its wings, and re- 

 mains as long as four bours beneatb tbe surface; yet it 

 exbibits no modification in structure in accordance witb 

 its abnormal babits. 



He wbo believes tbat eacb being bas been created as we 

 now see it, must occasionally bave felt surprise wben be 

 has met witb an animal having babits and structure not in 

 asfreement. What can be plainer than that tbe webbed 

 feet of ducks and geese are formed for swimming? Yet 

 tbere are upland geese witb webbed feet wbicb rarely go 

 near tbe water; and no one, except Audubon, bas seen 

 tbe frigate-bird, wbicb bas all its four toes webbed, aligbt 

 on tbe surface of tbe ocean. On tbe otber band, grebes 

 and coots are eminently aquatic, although tbeir toes are 

 only bordered by membrane. Wliat seems plainer tban 

 tbat the long toes, not furnished witb membrane of tbo 

 Grallatores, are formed for walking over swamps and float- 

 ing plants? The water-hen and landrail are members of 



