II— RANDOM STUDIES AMONG THE AMERICAN 

 CARABOIDEA 



The following isolated studies and generic reviews, together with 

 the preceding more monographic work covering the greater part 

 of the Platyninse, nearly completes the systematic treatment of our 

 Carabidae which I planned many years ago. The chief delinquents 

 in my collection now are the Clivinids and the genus Brachinus, 

 and these still remain in great part unidentified or even specifically 

 discriminated. Any efficient revision of Brachinus is impracticable 

 in the absence of direct comparisons with the types, and this, 

 because of their wide geographic dispersal, is a rather hopeless 

 task; there is such an extreme uniformity of design among the 

 species— of nearly the same kind as in Galerita—thsit the original 

 descriptions must be considered in many cases quite ineffectual for 

 purposes of identification. 



I have alluded previously (Mem. Col., VII, p. 2) to the iridescence 

 frequently observable on the elytra of the Carabidse, and have 

 stated that it is generally produced by a grating of very fine parallel 

 lines, producing a spectrum. This is often very conspicuous on 

 the elytra in the genus Loxandrus, the spectrum, with red at one 

 end and blue and violet at the other, moving forward along the 

 elytra when these are tilted at continually greater angle. Prof. A. 

 A. Michelson having investigated the metallic coloration of insects, 

 became interested on hearing this, and I gave him a specimen of 

 Loxandrus saphyrinus. Shortly thereafter I was informed by Prof. 

 Michelson, that he had examined the elytral sculpture of this 

 species and had found a regular optical grating, with lines about 

 1000 per mm., or 25000 to the inch. 



• 

 CICINDELID^ 



On comparing the series of Cicindela boulderensis and punchdata 

 in my collection, consisting of 25 and 27 specimens respectively, 

 it can be seen at a glance that there are two distinct species in- 

 volved; punctulata, occurring in abundance from Rhode Island 



13.^ 



