Miscellaneous. 415 
black- or plumbeous-coloured forms, examples of which I have seen 
from Mentone. 
Olivaceus, var. nov. 
Various shades of olive-green. Figured by Pollonera (op. cit.). 
I have examined specimens from Mentone. 
Flavo-qriseus, var. nov. 
Yellowish grey. Foot-fringe usually lighter than the body. 
From Mentone. 
It is difficult to separate some forms of olivaceus from this 
variety. 
On the Mechanism of the Production of Light in Orya barbarica 
of Algeria. By M. Rapuarn Dvusors. 
The discovery of the photogenous faculty in the Algerian Orya . 
barbarica is of relatively recent date. This fine Geophilid was 
observed for the first time, in a luminous condition, almost at the 
same moment by M. Raphael Blanchard at El Kantara (April , 
1888) and by M. J. Gazagnaire at Nemours (May 1888). 
Moreover, a certain number of important peculiarities were 
mentioned by M. Gazaignaire *; the phosphorescent substance is 
exuded from pores situated upon the sternal and episternal plates in 
the form of a viscid yellowish fluid, with an odour sw generis, 
drying rapidly on exposure to the air and insoluble in alcohol. 
In September 1887, on observing some specimens of Scolioplanes 
crassipes which had been sent to me from La Fere (Aisne) by 
M. Huet, I had myself remarked that the luminous fluid was 
excreted from the ventral surface of the body, contrary to an opinion 
which I had previously advanced; but I had not published this 
observation, since I intended to complete it later on. As I was 
unable to obtain fresh examples of Scolioplanes, I went to Algeria 
to look for specimens of Orya barbarica. 
Not only have I verified the accuracy of the facts recorded by 
M. Gazagnaire, but I have been able especially, thanks. to the 
employment of the microscope, of which this investigator did not 
avail himself, to make new observations which confirm in the most 
precise manner the correctness of the definitive theory of the 
mechanism of the production of light, as set forth in my last work 
| on Pholas dactylus f. 
| The facts which I have already recorded in various communica- 
| tions are correct, but their interpretation has sometimes varied in 
consequence of new discoveries ; to-day, however, uncertainty can 
no longer exist, owing to the facility for observation and experiment 
* J. Gazagnaire, “ La phosphorescence chez les Myriopodes ” (Bulletin 
de la Société Zoologique de France, t. xiii. p. 182). 
+ R. Dubois, ‘Anatomie et Physiologie comparées de la Pholade dactyle.’ 
Paris, G. Masson, 1892. 
