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THE AMERICAN NATURALIST [Vol. LIII 



is bright red or scarlet on the legs, head and neck, and red 

 and pink over the body generally; in the southern ostrich 

 the skin of the neck, 'body and legs is a pale yellow in 

 cliick^. dark uray in nintiirc licii^ and dark blue in cocks, 

 while in the -<'\nal!\ ripe ctick only the beak, the front 

 part of the head, the naked skin around the eyes and the 

 tarsal scales are a bright >earh't. The crown of the head 

 of the northern bird h,i- a h:dd o\ al patch while tliat of 

 the southern is covered with liair like feathers similar to 

 those over the rest of the head and nock. The northern 

 egg is larger and ronn<ler. witli an enanicl-like smooth- 

 ness, and is pi-an ieally free from ohvi(ni> pittings; the 

 southern is .leeply pitted all over, >nialler and more oval. 

 Knowing as we do the habits and life of the ostrich it is in 

 the highest degree improbable that any of the differences 

 have an adaptive significance or selective value in nature. 



When the birds are observed side by side, as can now be 

 done at Grrootfontein, the above characters readily serve 

 to separate the northern from the southern ostrich, and 

 may well be held to justify the specific distinction usually 

 accorded them. That the distinguishing features of the 

 former are not environmental but germinal is proved by 

 the fact that they ])cr.-i-t under southern conditions and 

 have reajopeared in piogenx already reared. Numerous 

 cross-breds oi- hybrids (.1* tlie lir>t generation have also 

 been obtaiiuMl, l»ut >nriieient time has not >('t intervened 

 to secure the -eeond hxhrid geiieiation. As regards di- 

 mensions, (•ok)r and the natnre of tlie egg the tirst gen- 

 eration of cross-l)reds nic internieiliates in varying degree 

 between the northern and >onthern jjarents, but the bald 

 head patch of the noithern i- dominant over its absence 



It i> elear that^ii.' germ pla>ni of tlie northern o^ti'ich 

 ha^ nnderuoiH- niarl<e.l ehan-e^ rompared uitl, tliat its 



think of the various i-ae,'> or .peeie- ,,t' Stnilhin a,^ (h^rived 

 from acommon >toek. In term> of the <e.-tional hea<rmg 



