of the Transition Formations of the Hhine, 19 



in the form or in the lobes. The principal part of this sec- 

 tion is composed of numerous species of the transition lime- 

 stone of the Fichtelgebirge, discovered by Count Miinster, 

 A, nodulosus, A. sublcevis, A. globosus, A. sublinearis, A. li- 

 nearis, A. divisus and A, hybridus. We may add as forming a 

 third subdivision, A, sulcatus and A. subsulcatus, Miinster, 

 which distinguish themselves by their lateral linguiformed 

 lobe, and are somewhat related to the following section : they 

 have nevertheless the lateral saddle broad and rounded, which 

 occupies the greater part of the side. 



Section III. ^quales. 



The dorsal lobe simple, linguiform or infundibuliform. 

 There are two or more lateral lobes, that become successively 

 greater or smaller in approaching the suture. 



6. Ammonites Becheri, Goldf. PL I. fig. 7^ 8. 



L. de Buck Goniat. p. 39. PI. II. fig. 2. 



The dorsal lobe infundibuliform; on the side which is 

 slightly vaulted are found four linguiform lateral lobes, which 

 become smaller and smaller in approaching the suture. 

 The first of these is twice as deep as the dorsal lobe ; the 

 fourth is but two-thirds the depth of the first, after it comes 

 a considerable ventral saddle that is twice as broad as the third 

 lateral saddle. The increase in height is 0*4, the increase in 

 breadth 0*65. There are seven whorls ; almost two -thirds of 

 the inner ones are enveloped. This Ammonite occurs in 

 the red limestone, amongst the Goniatites of Beilstein, near 

 Oberscheld ; it is also found in the hematitic iron of the mine 

 of Rinzenberg. It appears to come very near A, Henslowi, 

 Sow., but this has only three lateral linguiformed lobes. As 

 it augments much more quickly in height than in breadth, its 

 form is discoid, and the thickness rapidly diminishes. Its 

 contour presents an elliptical appearance, as always happens 

 when the height increases much faster than the breadth. The 

 shell is rarely well preserved ; it is thick and plaited : between 

 the folds are found regular spaces, with numerous finer 

 folds. The greatest thickness is near the suture ; the side 

 slightly vaulted falls gently towards the back ; the latter forms 



c 2 



