" On the Stigmatic Opercula in the 
Scorpion. " 
(By A. VAMAN PAI, from the Biological Laboratory, Presidency- 
College, Madras.) 
Communicated by Dr. Bourne. 
Last year, Dr. Bonnie called my attention to the fact that 
there is an arrangement connected with the pnlmonary 
stigmata of the Scorpion, by which the animal is enabled 
to open or close those apertures at will. Quite lately, I 
have been able to work out the subject more fully under 
his kind direction. 
An apparatus connected with the stigmata of Hexapod- 
Insects, by which they can be opened and closed has been 
described long ago.^ In the Scorpion the walls of the 
stigmata are strongly chitinised, and consequently cannot 
be brought together as in insects so as to shut off commu- 
nication with the exterior. But apart from the fact of such 
an arrangement having any connection with respiration, 
it is obvious that the animal would be liable to injury, 
if the access of foreign bodies to the pulmonary cavity 
cannot be prevented. The Scorpion has the habit of 
burrowing in earth and sand. During the monsoons it 
is frequently submerged in water. It is also necessary to 
protect the lung-books from noxious gases and vapours 
and to preserve them from desiccation. Hence it is clear, 
that it is necessary for the scorpion to possess some means, 
by which the stigmata can be 0]iened and closed at 
pleasure. 
^ Huxley's ' luverfcebrata ' page 375. 
