10 
cubo-octaédrons. The left hand figure below is from a 
continuation of the same Clay formation near Minster, on 
the Isle of Sheepy, and is from the inside of one of the same 
species, appearing more perfect; it has, however, none of 
the epidermis, and the pearly lustre is almost lost in an 
opaque whiteness; it serves well to shew the contour of the 
Shell; the dotted outline underneath shows the form of a 
septa, and the situation of the siphunculus: the middle 
figure is part of the largest siphunculus I have ever met 
with. This Shell is often found of a considerable size at 
Sheepy, and, as Mr. Trimmer informs me, at Brentford; 
at Highgate large portions have been found, and I met 
with three pieces that nearly fit, and when put together 
indicate a proportion larger, I believe, than usual for this 
species, viz. 12 inches for the longest diameter, 73 inches 
for the axis, and 8 inches for the shorter diameter, making 
a fine specimen. The largest piece has retained most of 
its epidermis, of a brownish buff colour, elegantly netted 
with dull Pyrites formed in knots or drops; the rest of the 
Shell is variegated and pearly ; and the last chamber, which 
is generally understood to be the habitation of the animal, 
is filled with marly Clay. I was about to give a folded 
outline of this in the work, but was persuaded to publish 
a full sized coloured figure, which I have done for the 
convenience of those who wish for such a representation. 
It may be understood, that, in general, while a Shell 
retains a pearly lustre, there remains some of the animal 
gluten. I ,,’e 1 specimen of this Nautilus from Brent- 
ford, by fay ;;, of Dr. Sutton of Norwich, which has some 
of the cutic , or filmy skin of one of the septa remaining 
quite elastic. partly covered with Pyrites. A specimen 
I have lately got from Highgate, besides Pyrites, contains 
fine spicule of Sulphate of Lime. 
It may not be amiss here to observe, that the Highgate 
