THE INFERIOR OOLITE OF DORSET. 



593 



Outer portion is the opposite, otherwise called the ventral area. 



Shoulder is where the inner portion of the whorl meets the pre- 

 ceding whorl, and is an important point in the diagnosis of Ammo- 

 nites ; some shoulders are square, as in Harpoceras Tessonianum 

 some concave, see Harp. Murchisonce ; some convex, some merely 

 sloping, <fcc. 



Termination or mouth-border, i. e. the completion of the body- 

 chamber. 



The termination is variously shaped : some have a plain semi- 

 lunar band, as Stephanoceras Humphriesianum ; others, ears of 

 various shapes, set up either nearly altogether on the ventral area, 

 as in/Steph. Braikenridgii, or on the sides and projecting straight, as 

 in Sphceroceras Sauzei (d'Orb.) ; others have a termination like an S, 

 as Harpoceras concavum; this is called the double bend; others 

 have this double bend with a horn projecting from the middle 

 others have a single bend, like Amaltheus spinatus (Bruguiere). 



In the following Tables I have roughly classified the Ammonite 

 according to their variously shaped terminations : — 



1. Semilunar termination. 



Stephanoceras Huniphriesiantirn( Sow.). 

 Cosmoceras Grarantianum (d'Orb.). 

 Stephan. polymer um (Waagen). 



Stephanoceras Deslongschainpsii (De- 

 fiance). 



Perisphinctes Davidsoni, S. S. Buckm. 



2. Semilunar termination, with a deep furrow first, and, sometimes, 

 a raised lip. 



Sphseroceras Gervillii (Sow.). 



Brongniarti (Sow.). 



Wrightii, S. S. Buckm. 



Sphseroceras Mansellii, J. Buckm. 

 diinorphum (d Orb.). 



3. Spathulate ears, projecting from a little on each side of the 

 ventral area. 



Stephanoceras Braikenridgii (Sow.), j Perisphinctes Martinsii (D'Orb.). 

 Blagdeni (Sow.). 



4. Ears like No. 3, but projecting from the side. 

 Sphseroceras Sauzei (d'Orb.). | Stephanoceras linguiferuni (d'Orb.). 



5. Termination, double bend without any horn. 

 Harpoceras concavum (Sow.). j Harpoceras cycloides (d'Orb.). 



Murchisonae, var. bradfordiense, 

 S. S. Buckm. 

 — Moorei (Lye). 



adicrum ( Waagen). 

 Haploceras oolithicum (d'Orb.). 



6. Termination, double bend ivith horn. 



Oppelia subradiata (Sow.). 



Harpoceras cornu, S. S. Buckm. 

 Cosmoceras Parkinsoni (Sow.)*. 

 Harpoceras Edwardianum (d'Orb.) 



Harpoceras Levesquei (d'Orb.). 



* I have placed it here on the authority of d'Orbigny's figures, my own spe- 

 cimen not showing the termination exactly enough. 

 Q. J.G.S. No. 148. 2r 



