A COMPARATIVE STUDY OF THE STRUCTURE 

 OF THE PHOTOGENIC ORGANS OF CERTAIN 

 AMERICAN LAMPYRID.E 



F. ALEX. McDERMOTT and CHAS. G. CRANE 

 Hygienic Laboratory. U. 8. Public Health and Marine 

 Hospital Service, Washington, D. C. 



Of the great amount of work that has been done in the 

 production of light by living forms, not a little has been 

 devoted to the structure of the photogenic organs. The 

 organs whose anatomy and histology have been the sub- 

 ject of most of the researches have been those of the 

 Lampyrida?. Although perhaps twenty-five species of 

 these widely distributed insects occur within the borders 

 of the United States proper, but little work has been done 

 on the anatomy and histology of their luminous organs. 

 The late Dr. Wm. H. Seaman (1) made some observa- 

 tions on Phot Urns py nil is, the insect which is so common 

 in the parks in Washington in the summer, and a near 

 relative of the pyralis, Phothius warr/incllns, has been 

 made the subject of an extensive study by Miss Town- 

 send, at Cornell (2). Wielowiejski (4) mentions having 

 studied two American species, but fails to give their 

 names. With these exceptions, however, the American 

 Lampyridap seem to have been neglected in the matter of 

 histologic studies of the photogenic organs. Of the for- 

 eign Lampyrida? which have been studied, the principal 

 species are Lampyris noctiluca, Phausis splendkhila, 

 Phosplucnus hnniptems and Luciohi italica, all Euro- 

 pean species, and ail belonging to different subgroup* 

 from each other and From the American insects. Many 

 studies have also been made niton the cucuyo. Pyrophorits 

 a <>< t Uncus Linn., the large tropical elaterid firefly. 



It has been thought worth while, therefore, to attempt 

 some further study of the photogenic organs of such 

 species of Lampyridae as are accessible here, having in 

 view especially the determination of the similarities and 

 differences between them and between them and other 

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