1922.] Characters III some Charadriine genera. 485 



similiirities, into a larger whole, and as obviously differentiated 

 into their respective genera. 



It has been suggested that the anatomical differences 

 which I have observed between the genera Squatarola and 

 Pluvialis, as also between Leucopolius and Charadrius, are 

 merely the result o£ differences ot" function and habits ; 

 in reply to which we can only put the question — Arc the 

 habits and functions of the Grey and Golden Plovers or of 

 the Kentish and Common Kinged Plovers so different that 

 such striking cranial differences as we have depicted could 

 conceivably have been produced, or was the environment of 

 the Grey and Golden Plovers or of the Kentish and Cou)mou 

 Ringed Plovers so different tliat it could possibly have called 

 forth such anatomical differences in response to it ? 



If the suggestion is correct *, it is a very remarkable and 

 astonishing fact that the habits and functions of the Grey 

 Plover of the Tundras, the Kentish Plover of Europe, and 

 the Ked-necked Plover of Australia are so precisely alike 

 that exactly similar cranial characters have in each case been 

 separately evolved in response to them in the three terms, 

 to say nothing about environment which presumably ought 

 to be similar too, in order to support the argument. 



The fact, too, that on the one hand the nestling 

 Kentish Plover {L. alecvandrinus) of Europe, the Snowy 

 Plover (L. nivosus) of America, and the Red-necked Plover 

 {L. ruficapillus) of Australia are so precisely alike, inter se, 

 that one can only with difficulty be differentiated from 

 the other, while on the other hand they are obviously 

 differentiated from the nestlings of the Oommon Ringed 

 Plover group {C. hiaticula, dubius, semipahnatus, placidus, 

 (fee), which in turn are as like to one another as two rows of 

 peas, seems to mc to suggest phyletic rather than environ- 

 mental inflaences {cf. PI. VI.). 



* * * * * 



What, then, is the explanation of these facts ? 

 Any attempt at an answer must necessarily be speculative 

 and suggestive ; and my suggestion is that in either of the 



* But see further on, pp. 488, 489. 



