238 Townsend, Use of Wings and Feet by Diving Birds. [xuly 



observations of Selous on other members of the group show that 

 the wings only are used. 



The Great Auk, with wings reduced to flipper-like proportions, 

 doubtless advanced rapidly through the water by the action of 

 these members only. 



The Penguins, although entirely distinct from the Auks, fly 

 through the water with their attenuated flipper-like wings, and, 

 according to Beebe (1) who has watched them in tanks," make but 

 little use of their feet in swimming, only occasionally aiding the 

 tail in steering." Evans (5) says: "When submerged, the wings 

 act as paddles with alternating rotary action, and the feet as 

 rudders, but on the return to the surface the latter naturally become 

 propellers." Lea (9) says of Penguins: "Their flight may be 



watched and studied in the large glass tanks at the 'Zoo' With 



short, rapid strokes of its paddle-wings it darts through the water 

 leaving a trail of glistening bubbles behind, and shoots forward 

 with the speed of a fish, turning more rapidly than almost any 

 bird of the air by the strokes of the wings alone, the legs floating 

 apparently inert in a line with the gleaming body, or giving an 

 occasional upward kick to force it to greater depths." 



Some of the Terns, in plunging for fish, disappear entirely under 

 water, and as their feet are comparatively feeble, and as their wings 

 are partially open in the plunge, it is possible that these latter are 

 used to some extent in aiding their progress, although it is probable 

 that the impulse of the plunge alone is all that is necessary. 



Among the Tubinares, some of the Petrels and the Shearwaters 

 plunge under water. Darwin (2) says of a diving Petrel, Pele- 

 canoides berardi: "When disturbed it dives to a distance, and on 

 coming to the surface, with the same movement takes flight. After 

 flying by the rapid movements of its short wings for a space in a 

 straight line, it drops, as if struck dead, and dives again.... It 

 would undoubtedly be mistaken for an auk, when seen from a 

 distance, either on the wing, or when diving and quietly swimming 

 about the retired channels of Tierra del Fuego." Lea (10) states 

 of the Capped Petrel, (Estrelata hcesitata, now nearly extinct: 

 "It poises itself in the air for a moment at a height of twenty or 

 twenty-five feet, and then, folding its wings, takes a header into 

 the water. The actual plunge is made with the wings open, and 



