438 C. R. Eastman — Another Egg of Struthiolithus. 



with BTiea the case is different. No one can deny that the physical 

 resemblances between Bliea and Struthio are very great ; in fact, 

 the popular term ' South American ostrich ' is an obvious com- 

 mentary on their similarity. Although both genera are regarded 

 as typical of distinct families, and are even commonly placed in> 

 separate subordei's, yet if one were asked to specify the nearest living 

 ally of the African ostrich, he would unhesitatingly point to Bhea. 

 Now either these resemblances are proof of actual blood relationship 

 between the two genera, or else they furnish a most marvellous 

 instance of convergence. The simplest, and as we believe, most 

 natural interpretation, would be to regard forms so like one another 

 as genetically related, at least until it is demonstrated that by no 

 possibility could they have been descended from the same stock. 

 To us it seems incredible that two separate derivatives of Carinate 

 birds should become specialized in exactly the same manner in 

 Africa and South America, and should assume such a close resem- 

 blance to one another, through the operation of fortuitous natural 

 conditions, or as the result of adaptation. For the chances are slight 

 indeed that the environment, of itself dissimilar, should act in such 

 a way as to produce an identity of ultimate results out of originally 

 heterogeneous material. 



If Ehea had different progenitors from the ostrich, we are in utter 

 ignorance as to what they were like, since no other descendants of the 

 parent stock can be pointed out. That there is anything in common 

 between Bhea and the Tinamous we cannot believe for a moment, 

 owing to the very different organization of the latter. Captain 

 Hutton's theory, therefore, which derives both Bhea and the moas 

 from a Tinamou-like ancestor which crossed into Australia and New 

 Zealand by means of an imaginary Antarctic continent, must be 

 relegated on both biological and geological evidence to the same 

 category as the Lemurian hypothesis. 



Ehea still enjoys a comparatively wide distribution in South 

 America, and its remains have been found in the bone caverns of 

 Brazil. If the evidence of Diatryma from New Mexico means 

 anything at all, it would point to a connection between a fossil 

 North American and the existing South American ostrich. It is 

 true that the late Tertiary yields no evidence of Struthious birds 

 in North America. But it is also true that until the discovery of 

 Struthiolithus under the shadow of the Great Wall in China, no one 

 could have suspected the whole intervening territory between North- 

 Eastern Asia, Russia, and South Africa to have been in comparatively 

 recent times inhabited by genuine ostriches. The palseontological 

 record is from the nature of things very deficient in the case of land 

 birds, and many gaps can be filled up only on indirect evidence. 

 One such hiatus is now partially filled by the occurrence of 

 Struthiolithus in Northern China. A race having the constitutional 

 vigour and numerical force to establish itself in this latitude — and 

 in a mountainous region as well, where the struggle for existence 

 is always intensified by a larger number of enemies than are 

 encountered on the plains, to say nothing of the rigours of winter — 



