SHORES OF THE CLYDE AND FIRTH. 
21 
if a race was determined on, he found himself heavily handi- 
capped, having a fine silky filament attached to his shell, 
and in his upward course was obliged to drag the mussel 
along with him. If, however, master winkle was left far 
behind through his heavy burden, he was not content until 
he reached the top, and triumphantly perched himself upon 
the back of the victor, who was now obliged to sustain the 
weight of both his captive brethren. 
From a microscopical observation of this filament, a 
gradual tapering from the middle towards the base was 
observable, with a staved-up appearance at the point of the 
attachment, which, I am inclined to think, goes to prove the 
original liquid condition before the drying-up process begins. 
Since these observations were penned, I had an opportunity 
of witnessing the creature's mode of byssus spinning. First, 
the foot is thrown out to whatever length required, and that 
in the first instance may or may not be to its entire length, 
the tip is then placed upon the object to be attached, and 
from that point to the base at the valves the membrane, 
conical-shaped, rises in a diagonal line, and for a short space 
of time remains perfectly motionless. Examining the under 
side of the foot, it will be found to be composed of contractile 
muscles, giving it the capacity of forming two edges along 
the whole length with a groove between; and when both 
edges are brought together the groove is formed into a 
sort of pipe or conduit. When the tip is attached to the 
object, the byssus fluid is allowed to flow down the conduit; 
and when it is completely filled the edges are again parted, 
and out falls the waxy-like thread, and the hardening 
process begins. The tip is again fixed upon another spot 
and the operation repeated ; and so speedily is the work 
accomplished, that I have seen as many as four threads, 
about an inch each in length, spun in the space of fifteen 
