shell; on it the radii are nearly equal in their thickness 
throughout, the external undulations are very prominent at 
. their commencement, and the keel projects but little, hence 
the whole has a flatter aspect than No. 4. I gathered it 
myself in the better light coloured Limestone of Shotover in 
Oxfordshire, about the year 1805. It is often found larger, 
but seldom so perfect. 
No. 4 represents a cast of the interior, the radii terminate 
with an acute prominence, from which they sometimes branch 
into the external undulations, these are not so prominent as 
in No. 2. ‘The margin or keel is also broader and thinner — 
than that of No. 2, its general contour is more uneven, and its 
sides appear more concave. I am much inclined to consider 
it asa distinct species. The specimen is a fine and instructive 
one, showing at the broad end the construction of the septa 
in an handsome manner, with the undulating and branching 
articulations which often give elegance to a specimen. This 
specimen is covered on the external part by an ochraceous 
iron: the inside is light coloured Carbonate of Lime crys- 
tallized. It was sent me from Somersetshire by the late 
Mr. Cunnington. 
AMMONITES quadratus. 
TAB. XVIL.—Fig. 3. 
Spec. Cuar. Involute, rather depressed, carinated, 
inner whorles half concealed ; surface with pro- 
jectmg furcate undulatmg radii entending into 
a crenated margin. Aperture obtusely square, 
in length about one-third the diameter of the 
shell. Volutions four or five. 
Ay inch and an half in diameter, and less than half an inch 
. thick, the radiating undulations are nearly regular in their 
thickness, they are forked about the middle of the whorle, 
where some short intermediate undulations commence with- 
out any regularity: the margin is not flattened. 
Robert Sparrow, Esq. of Worlingham Hall, Suffolk, 
kindly lent me this specimen; it is an hollow chambered 
cast in semitransparent Calcedony. It was found ina gravel 
pit at Brandestone, near Framlingham, Suffolk, in 1781. 
