39 



prior to the final moult. It appears, therefore, that this larviform 

 female is a mature though degenerate female, and that we have 

 not here to do with a case of paedogenesis ; i.e., of the larva 

 becoming sexually mature without the attainment of somatic and 

 metamorphic maturity. 



The same writer considered that we here "get a glimpse, so to 

 speak, into the remote past, from which has been handed down to 

 us, with but little alteration an archetypal Hexapod form which 

 prevailed before complete metamorphosis had originated." Were 

 this really the case, it is difficult to account for the occurrence of a 

 papal state in the individual development of the female, though this 

 might perhaps be interpreted as a partial transference from the 

 metamorphosis of the male. Further, if the larviform condition is 

 to be explained as a case of arrested development and the persistence 

 of a primitive type, either one would expect to find it fairly constant 

 in a group of closely related species, and genera evidently arising 

 from a common ancestry, or it must be considered as a kind of 

 throw-back or reversion to an ancestral type. 



For my part I prefer to regard the theory of degradation from an 

 earlier winged type as affording a better explanation of the facts as 

 we find them. We have the successive stages in such degeneration 

 all illustrated, from the fully winged though sluggish female of 

 Lnciola, through the brachypterous state found in the females of 

 certain species of I'hotinits, down through the apterous but other- 

 wise developmentally mature females of Lanipyris, and the more 

 degenerate type of female of Diojitoma to the completely larviform 

 females of i'liemjodes. The steps in this series do not imply 

 relationship or common ancestry, but merely indicate the points, 

 successively further and further back in the phylogeny of the group, 

 when the use of the wings in the course of any particular line of 

 development was discarded and their consequent degeneration set 

 in, or to put it briefly, that the apterous condition is of polyphyletic 

 origin. I know of no instance among the Lampyridte, such as we 

 have amongst Lepidopteva with apterous females (<?.//., Anisoptenj.v 

 (cacidaria) where, though wings are wanting in the adult, there are 

 well developed wing rudiments in the pupa, but I have found one 

 female of Laiiipi/yifi noctiliica, with the wing and wing-cover well 

 developed though shrivelled on one side of the body. 



With the question of the evolution of the apterous female is 

 bound up the question of the evolution of the power of luminosity. 

 Many members of the family Lampyridae are probably not luminous 

 at all. Pale yellowish abdominal spots are almost always to be 

 detected in the region of the luminous organ, but whether the species 

 possessing them are always luminous is open to doubt. Our 

 knowledge of the habits of many of these insects is extremely 

 defective, and it is frequently impossible to say from dried specimens 

 whether a species is or is not luminous. 



In most of the luminous species the eyes, particularly of the 



