( 7 «) 
into Threds’j which threds are reduced 
to two fbrtSj differing from each other 
in colour, fubftance and place. 
a. That in the little upper 
and under liiperfice are nothing elfe hut 
the extremes of the Threds; but the fu- 
perfice of the Limbtis ot Rim are the 
lides of the fame threds feituate in the 
Rim of the little Shell, 
5. That in the Shell it felf, the interi- 
our fuperfice is the fame with the interi- 
our fuperfice of the inmoft or greateft 
Shell; hut the exterior fuperfice is com- 
pofed of the exteriour fuperfice of the 
leaft Shell and of the fuperfice of all the 
Lims of the intermediat Shells. 
Touching the Manner, how Shells are 
produced, the particulars following may 
be evidently demonftrated j 
I. That the Matter of the Threds is 
like the fweat of Animals in this, that it 
is an humour excreted through the exf 
teriour fuperfice of the Animal. 
a. That the Figure of the Threds may 
be produced two manner of ways ; ei¬ 
ther in the very Pores of the Ahimalj' 
through which they arc excreted 5 or 
yyhilft the fuperfice of the growing Ani-». 
malj 
