AMMONITES— ZOOLOGICAL, ETC. 



101 



The first directed backwards, as regards the volutions, are as 

 M. von Buch has judiciously imagined, representatives of the 

 numerous digitations which existed around the mantle of the 

 animal ; and have served to fix it to its shell ; without them, 

 the syphon being dorsal, the animal would have been liable to 

 be tossed to and fro in its shell ; that this is the case is un- 

 questionable as the lobes are invariably acute in form, whilst 

 the saddles and their ramifications, which are always directed 

 forwards, are not, on the contrary, anything more than the 

 intervals comprised between the large or small divisions of 

 the lobes, and therefore always assume an obtuse form fre- 



Leopold von Buch indicate the different divisions of the lobes and 

 saddles. 



D. Dorsal lobe. 



L. Superior lateral lobe. 



L. Inferior lateral lobe. 

 First auxiliary lobe. 



a- Second auxiliary lobe. 



a^ Third auxiliary lobe, 



a* Fourth auxiliary lobe, &c. 



V. Ventral lobe. 



* v' First latero- ventral lobe separating from the ventral lobe. 



* v^ Second latero-ventral lobe, and so on. 

 D. S. Dorsal saddle. 



L. S. Lateral saddle. 



* s' First auxiliary saddle (the ventral saddle of Von Buch). I have 

 named it thus because it is frequently lateral when there are many 

 auxiliary lobes. 



* s^ Second auxiliary saddle. 



* s^ Third auxiliary saddle, and so on. 



* s v' First latero-ventral saddle (the saddle which separates the ventral 

 from the first latero-ventral lobe. 



* s v^ ^ Second latero-ventral saddle. 



The asteriks indicate the parts to which I have myself given names. 



