C ] 
which made the Tubercle in the Membrane (Sect. 
XII.)* It is much harder than the other contained 
Parts of the Head and Body 5 fo that it will bear 
cutting with the Scalpel. It is of a red Colour, as 
perfectly pellucid as a Drop of Water j of th'e Shape 
of a Pear, from a larger Bafis terminating in a Point. 
I cannot better refemble it to any thing than to the 
Cryllaliine Lens of the Eye : Yet in Spirit of Wine 
it preferved its Tranfparency, but its Bulk was dimi- 
nifhed (Fig. 7.5.). 
I cannot guefs its Ufe : It does not feem to me, 
as it does to fome, to be the Organ of Sight 5 for 
the Worm feems to have no Occafion for an Eye, as 
fpending its Life in perfctl Darknefs j befides that 
the invefting Membrane is not tranfparent, and there^ 
fore would obftrudt the Sight. 
Sect. XV. 
At the Sides, where the lower Edges of the He- 
nticrania do not touch one another, there is a fort of 
Cavity j and in thefe Sides the harder Fibres may be 
diftinguilhed, difpofed in fuch a manner, as perfedly 
to refemble the Gills of Fifh j and through them the 
Worm feems to breathe. 
Sect. XVI. 
The extreme $oftnefs of the other Parts of the 
Head prevents our coming at the Knowledge of the 
Ufe of the Membranes furniflied with Fibres of 
different Tendencies, or inquiring by vi^hat Organs 
the Worm takes the Wood fhaved off by the He- 
tnicraniay or rough Shells j whether it does this by 
Sudion, or not ; by what Mufcles, or how a< 5 ling, 
this 
