173 



eggs failed to hatch, except in irrigated districts. Also, in consequence 

 of the great drought and the drying up of all swamps, the birds, espe- 

 cially the '^mouettes" congregated in enormous swarms on the irri- 

 gated fields and speedily destroyed the young locusts. 



PHOSPHORESCENT CENTIPEDES. 



That there are luminous Myriopods has been known for many years, 

 as also the fact that they occur only among the family Geophilidce of 

 the Chilopod Myriopoda. Both sexes are luminous, sometimes quite 

 intensely so, and the luminosity spreads out over the whole ventral 

 surface of the animal. If one of these Geophilids is taken up the lumi- 

 nous matter communicates to the hand of the observer or to anything 

 else with which the specimen comes into contact. 



There is considerable dispute regarding the origin of this phos- 

 phorescent matter. According to Dr. R. Dubois it is contained in 

 the epithelial cell of the digestive tube and the emission of the light 

 depends on the moulting of the digestive tube. Mr. Mace, on the 

 contrary, contends that the luminous matter is a glandular excretion, 

 and that these glands {glandes preanales) are situated on the last two 

 segments of the animal. Mr. J. Gazagnaire has satisfied himself that 

 the luminous matter is secreted from glands situated on the sternal 

 and episternal plates. Upon pressure these glands secrete a yellowish, 

 viscous substance, having a peculiar odor and which is highly phospho- 

 rescent. 



In a more recent article (Mem. de la Soc. Zool. de France, v. iii, 1890, 

 pp. 136-146) Mr. Gazagnaire reviews all previous observations on lu- 

 minous Geophilids, and finds that, so far as the European fauna is con- 

 cerned, luminous specimens were found only between the end of Sep- 

 tember and beginning of November. The luminosity appears, there- 

 fore, only at a certain epoch in the life history of these Myriopods. Fur- 

 ther, in all more carefully recorded cases, luminous specimens were 

 never found singly, but always in pairs or in companies of three or more 

 specimens. The few and fragmentary observations that have hitherto 

 been made on the mode of reproduction in these animals seem to prove 

 that the fecundation of the female takes place in autumn, or just at the 

 time when the luminous specimens are found, and Mr. Gazagnaire is 

 thus fully justified in connecting the appearance of luminosity with the 

 excitement caused by sexual instinct. 



In Algiers, Mr. Gazagnaire observed luminous specimens of Orya bar- 

 barica in the month of April, and he concludes that in other countries 

 and in consequence of altered climatic conditions the period of lumi- 

 nosity probably differs from that observed in Europe. 



