374 INSECTA. 



palpi, or at least those of the maxillse, by their always soft, straight, 

 depressed, or but slightly convex body, and by the thorax, some- 

 times semicircular, and at others nearly square or trapezoidal, that 

 projects over the head, which it either entirely or partially covers. 

 The mandibles are usually small, and terminate in a slender, arcu- 

 ated, very acute point, that is generally entire. The penultimate 

 joint of the tarsi is always bilobate, and the crotchets of the last have 

 neither dentations nor appendages. 



The females of some are apterous, or have but very short elytra. 

 When seized, these Insects press their feet and antennae against 

 their body, and remain as motionless as if they were dead. Seve- 

 ral, thus situated, curve their abdomen underneath. They comprise 

 the genus 



LAMPYRIS, Lin. 



Antenna closely approximated at base, the head either exposed and pro- 

 longed anteriorly in the manner of a snout, or for the greater part, or en- 

 tirely, concealed under the thorax; eyes of the males large and globular; 

 mouth small. Such are the characters of a first division of this tribe, which 

 we will subdivide into those in which neither sex is phosphorescent, and 

 those in which the females at least are possessed of that faculty. Both sexes 

 of the former are provided with wings, have their head exposed, and fre- 

 quently narrower and extended anteriorly, OP in the form of a snout, and 

 the thorax widened posteriorly with pointed lateral angles. The two or 

 three ultimate annuli of their abdomen are destitute of that pale yellowish 

 or whitish tint, that is always found on this part of the body in the true 

 Lampyrides, and which announces their phosphorescence. The elytra, in 

 several, widen behind, and are sometimes strongly dilated and rounded 

 posteriorly, in the females particularly. They are densely punctured, and 

 frequently reticulated. 



The genera are Lycus, Dictyoptera and Omalisus. 



The other Lampyrides of our first division are distinguished from the 

 preceding ones, not only by the want of a snout, by their head, which, in 

 the males almost entirely occupied by the eyes, is entirely or for the greater 

 part concealed under a semicircular or square thorax, but also by a very 

 remarkable character, either common to both sexes, or peculiar to the fe- 

 males, that of being phosphorescent, whence the names of Glow-worms, Fire- 

 flies, &c., given to these Insects. 



Their body is extremely soft, the abdomen particularly, which has the 

 appearance of being plaited. The luminous matter occupies the inferior 

 part of the last two or three annuli, which differ in colour from the rest, 

 and are usually yellowish or whitish. The light they diffuse is more or less 

 vivid, and greenish or whitish, like that of the different kinds of phospho- 

 rus. It seems that they can vary its action at pleasure^ a fact particularly 



