310 THE CANADIAN ENTOMOLOGIST. 



As with scintillans and inargijiellus, the flash of the male is a single, 

 short, bright scintillation. The males of castus and marginellus were fre- 

 quently found flying together over the same plot of ground, and it proved 

 quite easy to distinguish them by the characteristics of their light-emission. 

 The flash of the male inarghiellus is decidedly shorter and more sudden 

 than that of the male castus. P. scintillans was not observed at this time, 

 and hence could not be compared. 



The female castus has the wings and elytra fully developed, but like 

 marginellus female, flies but little. The flash of the female castus is very 

 much like that of the female scintillans — a single, short scintillation, slightly 

 more prolonged than that of the male, somewhat less intense, and with no 

 indication of doubling (diff"erence from P. marginellus cT)- It is delivered 

 immediately after the flash of the male answered, without any distinct pause. 



The mating process in both P. marginellus and P. castus is exactly 

 the same as described for P. py rails and P. scintillans, and needs no 

 further comment. The females of marginellus and castus will not answer 

 with any certainty the flare of a match; in fact, in a large number of trials, 

 only one distinct answer, from P, castus cf was observed. As in the other 

 species of Photi?ii?ii heretofore observed, the females of these two species 

 are much less numerous than the males, and with marginellus the writer 

 observed for the first time among our Lampyrids the attempted coupling 

 between males, reported by Oliver (1er. Cong. Internat. d'Entomol., Brux., 

 1 9 10, pp. 143-144). While the females of both species fly readily they are 

 comparatively rarely found in flight, preferring to creep to the tips of 

 blades of grass, upper edges of leaves, etc., where they remain until mated. 

 As in the species of PJiotinus previously described, the luminous appara- 

 tus of the males of both castus and marginellus covers the entire ventral 

 surfaces of the 5th and 6th abdominal segments, and a good portion of the 

 4th, while the organ of the female consists of a small rectangular spot on 

 the 5th abdominal segment ; in both species the eyes and antennae of the 

 male are somewhat larger than those of the female. 



Where the males of both species were seen flying over the same area, 

 careful watching showed the presence of the females of both species in the 

 vegetation. Although especially watched for, no case of interbreeding was 

 encountered, and indeed no case of approach between the sexes of the 

 different species. In both species, flying males have been seen to respond 

 (apparently) to males of the same species in the vegetation. In both of 

 these species one will frequently find a pair in copula, surrounded by several 



