26 ENTOMOLOGICAL NEWS. [February, 



larity, which may be considered as the type of marking and illus- 

 trated by fig. i of the plate, representing vnlgaris is the under- 

 lying pattern from which all the forms observed in our Cicindelae 

 have been derived. 



Before going further it is well to present the following propo- 

 sitions that the argument and the illustrations may be understood. 



i. The type of marking is the same in all our species. 



2. Assuming a well marked species as a central type the 

 markings vary, 



, by a progressive spreading of the white. 



b, by a gradual thinning or absorption of the white. 



c, by a fragmentation of the markings. 



d, by linear supplementary extension. 



3. Many species are practically invariable. These fall in two 

 series. 



a, those of the normal type, as vulgaris, hirticoUis and tenui- 



signata. 



b, those in which some modification of the type has become 



permanent, probably through isolation, as marginipennis, 

 togala and lemniscata. 



4. Those species which vary do so in one direction only. 

 That is, supposing a species begins typically with markings 

 similar to vulgaris, the variation may be either in the direction 

 of thickening and increase of white as in hyperborea, generosa 

 and others, or in the direction of thinning or fragmentation of 

 the white with perhaps an entire loss of markings as in h<zmor- 

 rhagica, splendida, or obsoleta. 



The first two propositions must be considered as applying to 

 the species of the genus collectively, the last two to the species 

 separately. 



The accompanying plate has been prepared to illustrate these 

 propositions. It must, however, be understood that, in tracing 

 the derivations from the typical, it is not possible to use one spe- 

 cies as these modifications go on gradually through a number of 

 species, one sometimes beginning where another ends. 



In the plate fig. i represents vulgaris, which is a fairly typical 

 species, following through generosa (2-3), pamphila (4), hyper- 

 borea var. (5), togata (6), gratiosa (7), canosa (8), we finally 

 arrive at a perfectly white elytron as seen in some varieties of 

 dorsalis. 



