71 



AMMONITES Davoei. 



TAB. CCCL. 



Spec. Char, Depressed; sides nearly flat; vo- 

 lutions exposed, ornamented with numerous 

 transverse sulci, and a few distant, obtuse 

 tubercles ; aperture nearly orbicular. 



It is of little importance whether this shell be called 

 sulcated or ribbed, the sulci and spaces between them 

 are so nearly equal. When one coat of the shell is re- 

 moved these spaces are flat, as happens in Ammonites 

 annulatus, tab. 222, which this much resembles, the 

 distant tubercles being the distinguishing^ mark ; it has 

 also fewer whorls ; each tubercle covers, and as it were 

 attracts together about four of the sulci. 



Found in the blue Lias of Lyme Regis, in Dorset- 

 shire, and preserved by Mr. De la Beche. I have named 

 it to commemorate the present intelligent President of 

 the Royal Society, as I had formerly done the late 

 President. 



AMMONITES Brodioei. 



TAB. CCCLL 



Spec. Char. Largely umbilicate, gibbose, cos- 

 tated ; costae radiating, large and numerous, 

 terminated upon the sides of the whorls by 

 obtuse tubercles^ front rounded, plicated; 

 aperture transversely oblong, curved, 



Somewhat resembling Ammonites Brocchii, tab, 202, 

 but less gibbose and more strongly marked. The radi- 

 ating ribs are slightly curved : from each of the tubercles 



