426 ZOOLOGY sect. 



having been acquired by many Carinatas which have lost the 

 power of flight. The keel is very small in Ocydromus, Notornis, and 

 Aptornis, three flightless Eails — the last extinct — from New 

 Zealand, and is practically absent in the Dodo (Bidus) and Sohtaire 

 (PezopJiaps) — two gigantic extinct Pigeons from Mauritius and 

 Rodriguez, in the Kakapo or Ground-parrot {Stringops) of New 

 Zealand, in the extinct Giant-goose (Oncmiornis) from the same 



Fio. 1063.— Budjrptespacliyrliynclius fPenguin). Skeleton. (From a plirptograph 

 by A, Hamilton.) 



country, and in Hesperornis. The absence of the carina may 

 therefore be considered as an adaptive modification of no signifi- 

 cance as indicating affinity. 



The entire order of Penguins (Impennes) and the extinct Great 

 Auk (Alca inipannis) are also flightless, but their wings, instead of 

 being functionless, are modified into powerful swimming-paddles 

 (Fig. 1063). There has therefore, in these cases, been no reduction 

 either of the pectoral muscles or of the carina. 



