206 COLEOPTERA OF NORTH AMERICA. 



Antennffi with last joint appeiuliculate, having a small acicular ap- 

 pendage. Lampyees. 

 Antennae with second joint not transverse; head exserted, narrowed be- 

 hind the eyes. LucioljE. 



Group I. — Mathetei. 



In this group the front is wide, the antennae moderately sepa- 

 rated at the base, eleven-jointed, pectinate or bipeetinate, with the 

 last joint elongate, sinuate, and pointed at tip. The eyes are not 

 very large, lateral, convex, widely separated above and beneath. 



The prothorax is less prolonged over the head than in the next 

 two groups; the elytra are similar in both sexes and the inflexed 

 epipleuras are wide near the base, the extreme margin being 

 reflexed and elevated as far as the length of the metasternum; 

 this fold is parallel with the side margin in MalheteuH, but runs 

 obliquely towards the latter in Polyclasis. 



Margins expanded, flattened ; antenna3 pectinate. Matheteus. 



Margins not flattened ; antennae bipeetinate. Polyclasis. 



Group II. — Photini. 



In this group the antennae are more or less compressed, some- 

 times serrate; the last joint is elongate and rounded at tip, with- 

 out appendages or sinuation ; the second joint is short, sometimes 

 very short and transverse (Lucidota). The sexes are similar in 

 appearance, except in one species of Photinus, where the elytra 

 of the ? are short and the wings wanting. The eyes are larger 

 in % than 9, but are separated by a wide space both above and 

 beneath in all the species. In the % the last ventral segment is 

 small and narrow, covered by the scutate last dorsal, which varies 

 in form according to genus and species. The light organs, when 

 present, are more developed in % than 9, which is the reverse of 

 what obtains in the group Lampyres. The head is always covered 

 by the hood-like prothorax. The epi|)]eurae of the elytra are wide 

 at the base; the inferior (or distal) margin is reflexed, and con- 

 verges more or less to the lateral margin of the elytra. The elytra 

 vary in color; in the species without well-developed light organs 

 they are black, with the single exception of Pyropyga indicia, 

 where they are brown margined with testaceous, as in the brilli- 

 antly luminous species. 



It will therefore be especially necessary for the inexperienced 



