14 M. E. Beyrich on the Goniatites 



without a transverse plate. In order to see the lobes^ one must 

 take off a part of the last whorl, as is shown in fig. 2. In 

 the outer whorls the breadth of the opening at the mouth 

 is considerably greater than the height ; consequently the side 

 is very narrow, and the dorsal saddle, which is large and 

 rounded, can scarcely be distinguished. The form of this am- 

 monite would be perfectly spherical, if the inner whorls were 

 not partly disengaged, and thus form a large and deep umbi- 

 licus. Upon the last whotrl, destitute of transverse plates, the 

 side falls towards the interior in an obtuse angle, presenting 

 a well-defined ridge : this ridge is wholly wanting in the in- 

 terior whorls. The increase in breadth being more rapid than 

 the increase in height occasions the thickness in the inner 

 whorls to be a little less than that of the outer ones. The 

 back is also smaller in consequence, and the side more flat and 

 more distinctly separated from the back. For this reason 

 also the lateral lobe in the inner whorls is indicated on the 

 ,side by an imperfect curve of the transverse plate, whilst in 

 the outer whorls the dorsal lobe widens, and extends over the 

 back in such a manner that it has properly speaking no exist- 

 ence, except as a large and rounded dorsal saddle. 



In fig. 3, PI. I. the lobes are represented as they begin to 

 appear at first, in the specimen shown in figs. 1, 2, with a 

 whorl and half destitute of transverse plates ; in fig. 4 are the 

 lobes of another specimen, of which only the three innermost 

 whorls are preserved. The shell of this ammonite was striated, 

 as may be distinctly seen upon the cast : the striae are in- 

 flected behind, upon the back, according to the ordinary law 

 for Goniatites, forming a very deep curve. I have chosen the 

 name lateseptatus on account of the considerable distance of 

 the transverse plates from each other, which is so great that 

 there are only 10 or 11 of them in one whorl, whilst in general 

 14 seems the lowest Hmit for the number of transverse plates 

 of the Goniatites, 



3. Ammonites Dannenbergi, n. s. PI. I. fig. 5. a, h. 



The dorsal lobe infundibuliform, the depth twice as great 

 as the breadth ; the lateral lobe sinks a little deeper than the 

 dorsal lobe ; it entirely occupies the side and ascends towards 



