22S ^'E^V VORK ZOOLOGICAL SOCIETY. 



— the ilat, keelless slcrnuin — all ncctl vi surface for the insertion 

 of flight mtiscles having ceased long ago. 



The increase in size and power of the legs is perhaps the most 

 obvious adaptation of all. A two-fold function has resulted from 

 this change from the more slender, ancestral hind limhs. The 

 struthious birds have acquired the power to tlee swilily fnun dan- 

 s:er, and in addition, when at bav, or in defence of their voung. 

 the massive development of leg and foot provides them willi very 

 formidalile weapons of defence. 



In .\ptervx aloiie. in which llie cursorial habit is perhaps least 

 developed, there are four toes. Emeu, C"assowar_\' and Rhea have 

 three, while the Ostrich has but two. This latter bird >ho\vs an 

 interesting parallelism with the mammalian genus Jiqiiiis, in the 

 development of one toe at the expense of the others. At college 

 an athlete is told to run on his toes alone, and. instinctively, 

 throughout all time, those creatures, which have had {<> run for 

 their lives in life's great race, have followed this rule. The horse. 

 the kangaroo and the Ostrich have never broken training, and 

 all are tending toward the one-toed condition of the first-men- 

 tioned animal. In the kangaroo the fourth toe is the dominant 

 one: in the other two animals it is the middle, or third toe. upon 

 which all the stress comes. 



The voice of the struthious birds is as ]irimitive as many of 

 their other characteristics, and, though they have traces of some 

 kind of an ancestral syrinx, yet their utterances are in keeping 

 with their massive frames — reverberating rumbles, booms and 

 roars, which latter vocalization in the Ostrich so much resembles 

 the roar of a lion that it ma\ be somewhat (^f a protection against 

 their natural foes. 



Mr. J. G. Millais in his "Breath from the \'eldt" says that the 

 difference between the utterances of the two creatures is in power 

 rather than in quality or sequence of sounds. He illustrates them 

 in this wav : 



LION 



(crescendo) (diniiiuicndo) 



Moan-ROAR - R-0-.\-R-ROAR-Roar-roar-GruiU-grunt-gruiU-grunl-p;iunt-p;runt 



(dying away). 



OSTRICH 



(crescendo) 

 RUAR-ROAR-ROAR-R(JAR R-R-R-R-R (prolonged). 



