MR. BORLEY ON THE POISON APPARATUS OF THE WEEVER. 37I 
extent. The far more deadly opercular spine is hidden when 
the fish lies in its characteristic attitude, half buried in the 
sand with its dorsal fin erect and protruding. This probably 
explains the absence of any conspicuous pigment in the 
region of the operculum. 
The opercular spine is a process of the opercular bone 
(see Fig. 1). It is singularly like a flat dagger in shape, except 
that the guard and the handle fuse, and so do not make a cross. 
The edges of the dagger are grooved from tip to hilt, the 
grooves being quite distinct ; and where the blade joins the 
hilt the grooves continue as small pockets hollowed out of 
the opercular bone. 
The poison glands are pear-shaped masses of creamy white 
material of exceedingly lax and loose texture, whose broad 
ends are included in the pockets, whose side lies in the groove, 
and whose tip reaches nearly the end of the spine. They do 
not lie free in a cavity, but are surrounded and held in place 
by a network of connective tissue attached to the opercular 
bone, the opercular membrane and the spine. Their tips, 
however, lying in the grooves near the tip of the spine, have 
only a temporary covering, the groove being here roofed in 
by a loose sheath formed by the inturning of the surface 
layers of the skin. The disposition of this sheath cannot 
be understood without some little attention. It is perhaps 
best expressed by saying that where the spine issues from 
the substance of the operculum it is still at the bottom of 
a tube sunk in the operculum, this tube being the sheath. 
This tube wrinkles down about the spine as the latter enters 
a victim until about one- third of the spine is uncovered. 
The anatomy of the gland is known to us mainly by the 
work of Gressen in France, Newton Parker in England and 
Bottard in France. Our knowledge, especially of the histology, 
is, however, far from complete. I had hoped to exhibit 
sections of the gland at various levels and especially through 
the groove, where it is stated there is no true duct. 
Unfortunately the length of time taken in decalcifying 
my specimens has prevented this, and I am indebted to 
Dr. Evans for kindly furnishing me with slides of his own 
