34 
STIGMATIC OPERCULA IN THE SCORPION. 
tliat highly irritating and corrosive substances, such as the 
fumes of nitric acid, will make the animal shut the stigmata. 
Chloroform seems to produce some effect. But all the 
stigmata are not completely closed during the whole time 
that the animal is in it, a state of things which can be 
observed when the scorpion is put under water. In one 
instance, I observed in a scorpion which was placed in 
chloroform vapour, the stigmata which were previously 
shut, open after a time and remain in that condition, to 
within a short time of the animal's death. In another in- 
stance a scorpion which was in chloroform vapour for 15 
minutes was taken out almost dead and put on the table. 
The stigmata were shut at the time. After a while, they 
were found to be wide open, the animal being still per- 
fectly insensible and only exhibiting once or twice a slight 
movement- It afterwards recovered. 
To ascertain whether the pectines act as olfactory organs, 
I tried similar experiments on scorpions in which they had 
been previously removed. No difference was seen. It is 
probable that they act as tactile organs. AVhen a scorpion 
is walking or climbing up the sides of an inclined glass- 
jar, the pectines may be seen to move about and used like 
feelers. They possess a great range of movement. When 
the animal is uncomfortable, as when placed in chloroform 
vapour or gradually heated, the pectines may be seen 
moving after the rest of the body is still. 
In Thelyphonus, the openings of the two pairs of lung- 
books are hidden by prolongations of the sterna. Proba- 
bly, an arrangement exactly similar to that connected with 
the stigmata of the scorpion, does not obtain. These and 
other points in the anatomy of that interesting and little- 
known Arachnid, I hope to be able to determine on a future 
occasion. 
