778 RECORD OF CURRENT RESEARCHES RELATING TO 



young larvae will at once be likely to meet with their mollnscan diet. 

 The greater the tendency to produce ova in abundance the more 

 sluggish the females would become, and hence females once capable 

 of flight would lose the use of their wings, and the usefulness of the 

 light to attract their more volatile partners would be greater than 

 ever. This he believes to be the explanation of the fact that the 

 highest degree of light, or at any rate the greatest disproportion in 

 the amount shown by the sexes, is to be found in those species which 

 have apterous females, and together with this the greatest develop- 

 ment of eye in the male. 



The species in which both sexes are winged, and in which 

 both are luminous and in probably nearly equal degree, are, the 

 author thinks, by far the larger proportion of the whole number of 

 existing species. In this case the power of emitting light would be 

 obviously useful in attracting both sexes to assemble in swarms, and 

 it does not militate against this supposition that in many siDCcies the 

 males should possess this faculty in the higher degree. It might be 

 anticipated that if the female has to be guided to the rendezvous of 

 the species by this eilect, the eyes in that sex would not be inferior 

 to those of the male ; and such is the fact. One well-known case is 

 the European and Eastern genus Luciola. Here both sexes fly, both 

 are luminous, and both have largely developed, powerful eyes. 



Neither of these sections, however, comprise those species which 

 are generally regarded as most tyjjical of the family, the largest, and 

 those which appear on the whole to have all their parts most highly 

 specialized, and which, therefore, we place at the head of a systematic 

 list, such as the genera Lamprocera and Cladodes. It is rather re- 

 markable that in these genera the light-emitting faculty has not been 

 developed in the same proportion as the rest of the organs have, and 

 that while one of these, viz. the eyes, are also reduced in a direct 

 ratio with the light, and are small and uniform in both sexes, 

 another organ, the antennae, is developed in inverse ratio as the 

 phosphorescence is diminished. It is not intended to refer to mere 

 length, or redundancy in the number of joints, which are more usual 

 in very simple and primitive forms of the organ, such as we see in 

 JBlatta, but of a high degree of specialization, testified by large 

 lamellar plates or pectination. Whether the eye is develoj)ed at the - 

 expense of the antenna, and is so to speak the recei^tacle of all the 

 vital forces of the head, or whether the antenna supj)lements the loss 

 of the other organ of sense, and is useful in detecting the presence of 

 the female, only one fact is in evidence, which is that this j)lumosity 

 of the antennas, in one case, and this enormous development of the 

 eye in the other, are usually sexual characters predominating in the 

 male, but sometimes found in both sexes. 



In support of his view Mr. Gorham exhibited a selection of species 

 arranged in three groups, viz. : — 



i. Species with plumose antennae, small or moderate eyes, both 

 sexes winged, light-emitting surface confined to one or more small 

 spots : — Lamprocera, Cladodes, Vesta, Lucidora, Phcenolis, and Megalo- 

 phthalmus. 



