72 
that terminates them proceed about lour plaits or lesser 
ribs, that pass around the front, and meet the tubercles 
upon the opposite side : this part of the inner volutions 
is concealed. 
This shell was given me a long while ago, as found 
on Portland Island, but with some doubt, by my kind 
and worthy friend, Js. Brodie, Esq. whose name I wish 
to perpetuate : from the appearance of the stone I should 
rather suspect it to have come from the under or Iron- 
shot Oolite. 
AMMONITES peraraiatus. 
TAB. CCCLII. 
Spec. Chap. Depressed, armed with two con- 
centric rows of large pointed tubercles ; vo- 
lutions exposed, few ; front rounded ; aper- 
ture nearly orbicular. 
The tubercles are joined transversely by obtuse ridges 
into 18 or 20 pairs upon each whorl ; the remaining por- 
tion of the shell is even : it is rather remarkable that the 
tubercles are as sharp nearly in the cast of the inside as 
the outside of the shell : there are about four whorls : 
the aperture is in length about one-third of the diameter 
of the shell, and is rather longer than wide. 
A very conspicuous Ammonite ; found in the Pisolite 
at Malton, and given me by Mr. Alexander Crawford, 
of Scarborough. Besides other characters which distin- 
guish it from A. Birchii, tab. 267, the acute cast of the 
spines is a conspicuous one ; the size of these spines will 
distinguish it from a somewhat similar Ammonite not yet 
figured, found near Oxford. 
