182 
LECTURE XI. 
of pointed trunk, with which it touches the object 
it wishes to adhere to, and by retracting it, forms 
a glutinous thready and, by the repetition of 
this .motion, forms the whole tuft by which it is 
fastened. 
The large sea Pinna or Pinna rudis is a cu- 
rious instance of this. This shell is brown exter- 
nally, with a slightly iridescent silvery cast with- 
in ; of a lengthened shape, with a very narrow 
base, and dilated and rounded towards the extre- 
mity. It is a frequent inhabitant of the Euro- 
pean coasts, and in some places, as about the 
coasts of Sicily and Italy, the silken tufts are often 
collected, and spun into various articles of dress, 
as gloves in particular j the silk requiring no dj^e, 
but retaining its native colour, which is an ele- 
gant, glossy, yellowish brown. Specimens of this 
kind of silk are generally to be seen in most of our 
[Museums. Neither is this faculty of fastening or 
anchoring by means of silken fibres confined to 
the genus Pinna, but takes place, as we have al- 
ready seen, in the genus Mytilus, and probably in 
some of the rest. 
I now proceed to the Multivalve Shells » so 
named, as consisting of several valves or pieces. 
