312 THE CANADIAN ENTOMOLOGIST. 



A NOTE ON PHOTIlSrUS CASTUS LEG. 



BY F. ALEX. MCDERMOTI, PITTSBURG, PA. 



During the course of the observations recorded in the preceding 

 paper, it became evident to the author that the insects usually classified 

 as Photimis marginelhis and Photinus viarginellus var. castus, are actually 

 distinct species. As brought out in the foregoing paper, the manner of 

 the light-emission of the males of the two differ somewhat, and that of the 

 females very distinctly. Such distinctions among the Lampyridae cannot 

 be other than specific, especially in view of the very close resemblance 

 which many of the known distinct species bear to one another, and while 

 a definite boundary between species and varieties, which is satisfactory to 

 everyone, has not bsen established, and possibly never will be, it still 

 seems proper to consider that when a Lampyrid shows such differences 

 from other forms in its manner of light-emission as to almost preclude the 

 possibility of interbreeding, it is due the position of a distinct species. 



LeConte established the species ^^ Photinus casta'' for an insect from 

 Georgia, U. S. A., in the same paper in which he established "P. 

 7ttarginella'' for specimens from Missouri and elsewhere. (Proc. Acad. 

 Nat. Sciences, Phila., 185 1, p. 335) Subsequently he appeals to have 

 abandoned this arrangement, and grouped the ^^casta'' as a variety of 

 '■'■marginella'' and in his List of the Goleoptera of North America 

 (Miscellaneous Gollections of the Smithsonian Institution, No. 140, p. 51, 

 1866), he gives Photinus m.irginellus var. castus; this is the earliest 

 reference to the change in the classification of this insect which I have 

 been able to locate. The insect is thus listed as a variety of marginelhis 

 in the Genminger- Harold Catalogue (Vol. 6, p. 1,643), ^"^ ^" Y^xn. 

 Olivier's recent lists (Wytsman's Genera Insectorum, Fasc. 43 ; Schenk- 

 ling-Junk Catalogus Coleopterorum, Pars 9). 



In view of the specific differences in light-emission, above referred to, 

 it has seemed best to re-establish the species under LeConte's (corrected) 

 name. The species differs from the other species heretofore described in 

 these papers, most particularly in the pale gray colour of the elytra ; by 

 transmitted light the latter appear to be almost pigmentless, except at the 

 margins; the central black spot on the disc of the thorax is sm ill and 

 more frequently wanting than in the true marginellus ; the insects average 

 somewhat larger than either P. marginellus or P. scintillans, but are 

 distinctly smaller than P. consanguineus. 



The writer is indebted to Dr. Samuel Henshaw for his kindness in 

 comparing specimens sent him with LeConte's types in the Museum of 

 Comparative Zoology. 



