34 J. L. LECONTE, M. D. 



% with last dorsal segment emarginate, seventh ventral truncate, and 

 eighth small. The light organs in the $ are at the sides of the seg- 

 ments, which are dusky or piceous at the middle, and with distinct 

 stigmatiform pores; the last dorsal and ventral are of usual form, 

 presenting no peculiarities. This genus corresponds with Pyrectosoma 

 Motsch., (Et. Ent. 1853, 38), but the specific name verncolor, which he 

 attributes to the type, belongs to a species of Photuris. 



Elytra with narrower side margin 2. 



Elytra with wide side margin, surface opalte, alutaceo-granulate, not punctured, 

 discoidal costse well marked; antennae as long as prothorax; ventral seg- 

 ments 5 testaceous, spotted with dusky; 7.5 — 12 mm.; Can.; Mass.; Ill,; 



Ga 1. angulata Say. 



2. — Antennae shorter than prothorax 3. 



Antennae longer than prothorax. 4. 



.3. — Elytra not punctured, discoidal costse well marked, abdomen 9 i'l great part 

 dark; 8.5 — 15inm. ; Me.; Mass.; Can.: L. Sup. ; Tex.; Montana. 



2. borealis Rand. 

 Elytra densely punctured, discoidal costse obsolete ; abdomen 9 yellow, spotted 



with piceous; 14 mm.; Fla 3. nitifliventris Lee. 



4. — Narrower, ventral segments 1 — 4 piceous, seventh witli a piceous spot; 9 fifth 

 and sixth j^iceous, with sides and hind margin yellow ; light organs smaller 

 tlian in the otlier species ; 8.5 — 15 mm.; Mass.; Mich.; Pa.; Ga.; Tex. 



4. lucif'era Mels. 



PHOTINUS Lap. emend. Lee. (nee Lacordaire). 



This genus as emended by me (Pr. Ac. Nat. Sc. Phila. 1852, 33-1), 

 differs from the preceding by the prothorax not at all carinate, but 

 usually slightly channeled, and more obtusely rounded in front. The 

 surface is pale, tinged with rosy, and is usually marked with a dusky 

 spot or stripe. The light organs are always larger in the % than in 

 the 9 , and in the latter sex vary considerably according to species ; in 

 the % they occupy the whole of the ventral segments from the fourth 

 or fifth inclusive ; on the fifth and sixth segments the stigmatiform 

 impressions are very distinct, except in the division Gynaptera^ where 

 they are nearly obsolete ; in the 9 the light organs occupy the middle part 

 of the ventral segments, and exhibit themselves mostly as a flat elevation 

 on the fifth segment. The stigma-like impressions are barely or not visible 

 in the 9 , which may thus be easily distinguished from the 9 of the species 

 of the preceding genus. Some of the species are among the most abundant 

 and beautiful of our lightning bugs, though less gregarious than Photuris. 



exist, but with a purely normal respiratory function. It may be affirmed with 

 great probability, that these impressions are homologous with the ventral setigerous 

 pores or fovese of Carabidse and Staphylinidse, which bear the so called ambulatorial 

 setse. In Lampyridse these fovese are conspicuous only in this and the following 

 genus (Phoiinus), so far as the genera occur in our fauna. 



