214 



FOOT-NOTES TO EVOLUTION. 



Studies increased the number of these species, until at 

 last a large proportion of our birds were represented by 

 Eastern, Western, sage brush, and prairie species. Some- 

 times these closely connected forms were distinguish- 

 able at first sight, as in the case of the yellowhammer 

 and its double, the red-shafted flicker ; in other cases 

 baffling the most skilful, as with the two species of 

 crow-blackbird. 



An illustration of these forms and their relation may 

 be taken from the common shore lark and its varieties, 

 although it is fair to say that some of these variations 

 have never been regarded as species. 



The shore lark or horned lark [Otocoris alpestris), 



ranges widely over the colder and open parts of Europe, 



Asia, and America. The common form, 

 The shore l3,rks 



called alpestris^ is familiar to most of us. 



In the northwestern region, as far south as Utah, is 

 another form, equally large but paler in colour {leuco- 

 Icema). In the prairie region the lark is of the ordinary 

 colour but smaller {prattcola). In the sage plains it is a 

 similarly small but pale lark, with brighter yellow in its 

 throat ; this is arenicola. In Texas the bird is still 

 smaller and grayer [giraudi) ; while the small form found 

 in New Mexico and Arizona has its plumage strongly 

 washed with red ; this is chrysolcema. In the interior of 

 California the shore larks are still smaller and redder 

 (variety rubea), while northward and coastwise appears 

 a small lark with more streaked plumage — this is siri- 

 gata. All these can be generally recognised by an ex- 

 pert ornithologist, and doubtless a closer analysis would 

 reveal the basis for still finer subdivisions.* 



* In the Auk for April, 1890, is an essay on tlie Horned Larks 

 of North America, by Jonathan Dwight, Jr. Mr. Dvvight's con- 

 clusions are based on two thousand and twelve specimens ; those 

 of Mr. H. W. Henshaw, above given, on three hundred and fifty. 



