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THE AMERICAN NATURALIST. [Vol. XXXV II I. 



as the consequence of geological changes ; that we can point out 

 the modifications which have taken place in the species and, to a 

 considerable extent, we can trace the geological phenomena 

 which are the fundamental or underlying causes of the modifica- 

 tions. Of course not all species will be equally affected by^ 

 changes in their environment, nor will the modifications neces- 

 sarily be parallel. Minute differences in the organic structures 

 of insects indicate a probable diversity of physiological charac- 

 ters, and varying physiological activities may well modify such 

 details as patterns of coloration or even the colors themselves. 



As an example of an insect which has, in all probability, had 

 its range determined and its specific characters modified by a 

 series of geological changes, the history of which is not too 

 remote and therefore fairly well known, we may take that aggre- 

 gate of forms of Cicindela described under the names C. echo 

 Casey and C. pseiidosenilis W. Horn. These are without doubt 

 modifications of one type ; in fact they are so closely related as 

 to be separable only in series. They are also very close to C, 

 tvillistoni, and are ranked as races thereof by Dr. Walther Horn- 

 However, the exact status of these names, specific or subspecific, 

 does not concern us at present ; the fact remains that these 

 forms are closely related and may well have come from a com- 

 mon stock. Cicindela fulgida, to which zvillistoni was formerly 

 referred as a variety or race, is readily separable by the thickly 

 haired front. It may perhaps be an older offspring of the same 



I he ways in which the beetles differ from one another may 

 he hncHy outlined, in order that the reader may understand the 

 relationships and the better appreciate the account of the varia- 

 tions oi each. It must be borne in mind that the descriptions 

 reter more especially to series of specimens than to individuals, 

 unless definitely stated to the contrary. 



iicindcla fulgida Say. Easily separated from the allied spe- 

 cies by the tront being thickly hairy. The color is usually more 

 coppux K'd. though specimens occur at Lincoln, Nebraska, in 



^'^^^ '"^'^ .!;i"un(l Color is nearly black. Markings moderate, 

 .now as a rule, the middle band not expanded along the 

 ni'-^rgm (or but very slightly so), the humeral lunule very oblique 



