PLATE V. 



Fig. 



1. AinmonUes hrodicei, J. Sowerby, Miu. Conch., vol. iv, p. 71, 1822, pi. occli. [Brit. Miis. uo. 43905.] 



" Specific Characters. — Largely uinbilicate, gibbose, costated ; costse radiating, large and numerous, 

 terminated upon the sides of the whorls by obtuse tubercles, front rounded, plicated ; aperture 

 transversely oblong, curved. 



" Somewhat resembling Ammonites hroccJiii, tab. 202, but less gibbose aud more strongly marked. 

 The radiating ribs are slightly curved : from each of the tubercles that tei'minates them proceed al)out 

 four plaits or lesser ribs, that pass arouud the front, and meet the tubercles upou 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, Jas. 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 Ironshot Oolite." 



[See also PL VII, fig. 3.] 



Fig. 



2. Ammonites parTcinsoni, J. Sowerby, Miu. Couch., vol. iv, p. 1, 1821, pi. cccvii. [Brit. Mus. no. 43925.] 



" Specific Characters. — Discoid, with numerous highly elevated radii ; whorls numerous, the inner 

 ones exposed ; radii slightly arched, bifid near the front which is very narrow and plain. 



" Volutions numerous, with slightly convex sides and narrow edges : the arched radii are bent 

 forward at their outer ends, aud nearly meet at an acute angle upou the front, but do not jjass over 

 it : the edge of the shell is nearly flat, in the cast it is hollow in consequence of the removal of the 

 siphuucle ; the aperture is oblong, narrowest towards the front. 



'■ This is the Ammonite so frequently split, polished, and sold at Bath : its outer surface is also 

 ofteu ground and polished, showing ramifying, sinuated, or simply undulated edges to the septa, 

 according to the depth to which it has been worked. Misled by worked specimens that had lost the 

 flat space in the middle of the edge, I have erroneously referred this spiecies to the Am. giganteus, 

 at page 55 of vol. i while speaking of such as are found near Keynsham, and those fine specimens 

 given me by Dr. Lettsom, all of which are flatter than even the variety a of the giganteus, and have 

 more whorls. The species before us occurs chiefly in Lyas, a stratum not known to contain any 

 silicious deposit; it is consequently never imbedded in Chert or Flint, like the A. gigaidciis ji. I 

 suspect it also may be found in the lower beds of the Ironshot Oolite, as the specimen now figured is 

 from near Yeovil, and contains vestiges of ferruginous grains. I am indebted to the kind attention 

 of Dr. W. E. Leach for preserving it from the gothic hands of the mason, who is often as desti-uctive 

 of the essential characters of fossils, as some dealers still continue to be of the natural forms of recent 

 shells, and who rob them without mercy of venerable coats that had resisted with various success the 

 combined efforts of numerous sea-born enemies, whose ravages even leave marks more worthy of 

 contemplation than the formal beauty betrayed by the file or polishing brush. . . . 



"A section, showing the chambers filled partially with crystallised Carbonate of Lyme, is given at 

 tab. 12 of British Mineralogy. It often extends to IS inches or more in diameter, and when cut thin 

 and viewed by transmitted light, offers a specious excuse for the tmscientific mason." 



