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 (Ofocoris alpestris), 
ranges widely over the colder and open parts of Europe, 
Asia, and America. The common form, 
called a/festris, is familiar to most of us. 
In the northwestern region, as far south as Utah, is 
another form, equally large but paler in colour (Zeuco- 
lema). In the prairie region the lark is of the ordinary 
colour but smaller (frazicola). 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 (g¢vaudi) ; while the small form found 
in New Mexico and Arizona has its plumage strongly 
washed with red; this is chrysolema. In the interior of 
California the shore larks are still smaller and redder 
(variety rzdea), while northward and coastwise appears 
a small lark with more streaked plumage—this is s¢rz- 
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.* 
The shore larks. 
* In the Auk for April, 1890, is an essay on the Horned Larks 
of North America, by Jonathan Dwight, Jr. Mr. Dwight’s con- 
clusions are based on two thousand and twelve specimens ; those 
of Mr. H. W. Henshaw, above given, on three hundred and fifty. 
