10 
AMMONITES communis. 
TAB. CYII. — Figs. 2 5 and 3. 
Spec. Char. Involute; volutions six or more, 
exposed; radii annular, prominent, split over 
the front; aperture circular. 
Svn. Corne d’ Ammon a raies doubiees vers le haut 
du dos. Bourguet , $c. pi 42. /. 276. 
The aperture about one-fifth the diameter of the shell. 
The radii, which in the cast commence quite at the inside 
of each whorl, are continued nearly straight to the round 
front, over which they are sometimes forked and sometimes 
divided and united again on the opposite side. 
This species, varyiug a little, is very common in the 
Alum Clay at Whitby; it is mostly dark coloured cal- 
careous marie, shining with pyrites. The Ammonites are 
called in common Snake-stones, and superstition has ac- 
counted for their having been found constantly without 
heads, saying, the curse of St. Cuthbert was the cause of 
it; but as some of the dealers felt it a possible inconvenience, 
they were determined to be less barbarous, and compassion- 
ately supplied some with heads. I was so curious as to de- 
sire to see what sort of heads might be substituted, and Lady 
Wilson kindly procured me a specimen when at Whitby. 
I have figured that specimen for the information of others ; 
see fig. 2. The beatiful Keynsham Ammonites are also 
called Snake-stones, having been changed into stone by 
some devotee for the benefit of his brethren. Fig. 3 is a 
small specimen, showing something of the section and sep- 
tum, which is nearly round, exclusive of the space occupied 
by the inner whorl. 
This species is perhaps among the fossil Ophiopomor* 
phites of Plott. 
