18 



crest of these waves to be again presently affected by half-a- 

 dozen little additional waves, and these half-dozen to each assume 

 an arborescent form, and the whole suddenly to become rigid, you will 

 perhaps realise the floors and ceilings of the Ammonite's dwelling, 

 FlG jj which in contact with the outside walls, present 



radiating lines of a foliaceous pattern in the cast 

 of the shell. 



A foreign geologist, M. de Buch, investigated 

 these complex waves on the surface of the floors 

 and found, wonderful as it may appear, that every 

 species of the family has its own wave-pattern, 

 impressed upon its sides, and is thus stamped, as 

 sketch of Ammonites it were, with its own proper name, written in a 



splendens (Gault) show- .. . 1 T _^. 



ing the leaf-like traces writing which was penned by the Most High m 



of the undulating Septa, 



depicted on the sides of the primseval affe. 

 the fossil. £ 



Numberless almost are these species of Ammon- 

 ites. 1 Already something like eight or nine hundred have been de- 

 scribed ; and this has by no means exhausted the list. Nay, 

 wherever the Palaeontologist sets his foot, and seriously sums up 

 the Ammonites at his 'disposal, fresh forms and fresh shapes reward 

 his research. 



These species were not created at haphazard and scattered over the 

 ancient world, just as a sower sows his seeds ; on the contrary, first 

 one particular type was founded, and then another, and this so 

 marked, that if an Ammonite is placed before a person versed in such 

 learning, he can tell from its style of ornament and curvature 

 whether it came from the Liassic, Oolitic, or Cretaceous beds. 



It would weary you, to give you these type groups, it will suffice 

 that they comprehend about 21 sets, 2 named the tuberculated, the 

 sickle -bearing, the narrow-ribbed, the crowned, and so on, significant 

 of the particular ornamentation and appearance special to each group. 



Each Ammonite — as one of a species or family, say (to be 

 familar) that of Smith or Eobinson — had few ancestors, Smith soon 



1 In Morris' Catalogue of British Fossils, 1854, all the English species of Ammon- 

 ites descrihed up to that period are noted. 



« Von Buch and D'Orbigny have treated this idea at some length; illustrations and 

 remarks will be found in Chenus' Manuel de Conchy liologie, 1859. 



