134 -IMKKICA.V X.i rrRALIST. [Vol. XXXVIII. 



adjoining cylinders. Emery, from his work on Luciola, confinns 

 the views of Wielowiejski in all points except as regards the 

 anastomosing of the capillaries. He found them always ending 

 free, never uniting with those from the same or another 

 cylinder. 



In this work the nomenclature previously used has been 

 retained except in a few cases where a change seemed especially 

 advisable. The more familiar terms phosphorescent and lumin- 

 escent, with their nouns, are abandoned and photogenic and 

 photogeny sub.stituted. Phosphorescent is objectionable as it 

 suggests that the light is due to the presence of phosphorus. 

 Photogenic — light-generating — gives a more definite idea of 

 the actual phenomenon than luminescent. The name *'end 

 cells" was used by Max Schultze because he believed the 

 tracheiTi had their ultimate endings within these cells. Now 

 that it is proved that the tracheae do not so end, but merely pass 

 over into the tracheolar network, the name "transition cells," as 

 used by Holmgren ('96), is far preferable. The term tracheoles, 

 which is used elsewhere in insect histology to designate fine 

 trachael branches not possessing spiral thickening, is prefer- 

 able to " tracheal capillaries." 



1 he light -organs of the male of PJiotinus man^im-llns are in 

 the toim of two plates King aboxe the xuUial b..d\ uall of the 

 fifth and sixth abdominal seg- 

 ments. (Figs. I and 2.) The 

 underlying cuticle is trans- 

 parent, allowing free emission 

 of the light. The plates lie 

 just beneath the central nerv- 

 ous system and directly up(ni 

 the very thin h\p(xlerniis. 

 They are yellowish white in 

 color. In the female of the 

 'IV sj.rnos there is onlv a single, somewhat spherical organ 

 tlK- c t ilt IV ot the htth segment- In this work all descriptions 

 stuuuitc Ktei lo the hght-organs of the adult male. The 

 nn ti.ulua ot the photogenic segments send branches ventrad 

 tougii the hght-organs. Thus the dorsal surface in fresh 



