362 



NATURAL HISTORY OF ARTHROPODS. 



develop under favorable eircuinstanees in a year, bnt many of tlieni require several 

 years to attain full growth. 



The Elateridre not only show their relationship to the Lampyridaa by anatomical 

 characters, but also by the ])ossession of luminous organs in a few species, these lumi- 

 nous organs being found in the larva; of a number of species, and being long since 

 observed on the iniagos of Pijroplioriis. 



Fjn. 413. — Stages of an Elali-iid {Alnu>:^. 



The true Elaterida^ have the jiosterior co.\;v laminate, and the labrum visible and 

 free. Melanactes, pkeus is a very shining, black species, about one incli long, found 

 upon the Atlantic coast of North America as far north as Massachusetts. M. morio, 

 a somewhat smaller species with striate elytra, is found in the same regions. Larva\ 

 suppoised to belong to 3Lilanactes, are quite brilliantly lununous. 



It is, howevei-, to the genus Pi/ropliorus, which contains about a hundred species of 

 Elaterida', all from trojiical iVmerica, th.'it we must turn for the most brilliant forms 

 of luminous insects. Pi/roptioriiit noctilucus, common in the West Indies and Israzil, 

 and in common with a few allied species called the ciicmjo by the West Indians, is 

 from 1.50 to 1.75 inches long. Its color is a rusty brown, ajjproaching black. Upon 

 each side of the protlK)ra\-, near its basal angles, is a convi'x, oval lantern, which, 



