MALACODERMATA. 259 
Very closely allied to P. congruus, Chevrolat, some of the varieties of which com- 
pletely resemble it on the upper surface; but having now examined a large series of 
both, I have no doubt of their specific distinctness. ‘The antenne are shorter in the 
male ; when the head is extended in P. incongruus they do not reach further back than 
the posterior edge of the metasternum, while in P. congruus they will be longer by the 
two or three apical joints. M. Chevrolat did not distinguish the sexes of P. congruus, 
but simply says the three apical segments of the abdomen are traversed with yellow. 
The fact is that the basal segments in the male of that species are pale fuscous 
margined with whitish yellow, the basal half of the fourth and all the apical ones are 
pale, and the pygidium is subdiaphanous ; this latter character I find to be always fixed. 
The female also (and I have a type from himself) is wholly pale at the apex of the 
abdomen, not partly infuscate as in P. incongruus. 
The pale vitte of the elytra are generally costate, with the nervure conspicuous in 
P. congruus, and the lateral margin is dark. In P. ¢ncongrwus there is only one 
discoidal vitta quite even, and of equal width, and the margin is pale. The whole 
insect, and especially the thorax, is narrower. 
Mr. Champion found this species in dense virgin forest on the Volcan de Chiriqui, at 
the altitude of 5000 to 6000 feet, and not lower. 
Photinus incongruus, var.? 
Pallidior, vitta discoidali vel egre distinguenda, vere omnino obliterata. Long. 12-18 millim. ¢ 9. 
Hab. Panama, Volcan de Chiriqui, alt. 2000 to 3000 feet, Bugaba (Champion). 
At lower altitudes on the Volcan de Chiriqui Mr. Champion met with a few speci- 
mens of a Photinus, which only differ from P. incongruus in the pale fuscous colour of 
their elytra. The specimens from Bugaba are altogether without a vitta, and one of 
them is smaller than any other specimen I have seen, while those from an intermediate 
altitude have the vitta faint. Thus we may expect to find traces of other species at 
different altitudes ; and the darker or melanic forms occur both in higher latitudes, as 
well as in the cooler regions of mountain districts. 
I have observed the same effect to be produced in Photuris pennsylvanica, a species 
which is somewhat similarly marked to this species. 
2 (a). Photinus ignis-fatuus. 
Nigro-fuscus ; thorace albido subdiaphano, disco nigro, utrinque miniato. Long. 19-21 millim. 3. 
Mas. Segmentis quinto et sexto ventralibus lete flavis, marginibus profunde excavatis, apicalibus cum pygidio 
pallidis. 
Femina. Segmentis tribus apicalibus albidis. 
Hab. Panama, Volcan de Chiriqui (Champion). 
Allied to P. meteoralis, but differs in the ventral luminous parts, especially those of 
the male. 
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