104 



THE GEOLOGIST. 



lobes I have mentioned. At this period, the lobes and 

 saddles indicate the grand divisions they ultimately attain ; 

 they are equal or unequal in their ramifications ; but the 

 ramifications are in the most simple condition, frequently 

 shewing but a single point for each future main branch, or 

 a large festoon, to represent the division of a saddle, which 

 ultimately becomes deeply foliated. Thus, all the com- 

 ponent parts, as in Ammonite itself, are in their most 

 simple state, with this difference, between the external and 

 internal characters, that the Ammonite already presents all 

 the indications of the characters of the lobes it ultimately 

 obtains, whilst it does not present any of its ultimate ex- 

 ternal ornaments. 



2.— From this period until death, the Septa do not 

 undergo the same alterations as the external appendages. 

 They become more complicated as the Ammonites increase 

 in age, and never degenerate. There is then, in this respect, 

 a complete dissimilarity between the internal characters, and 

 the external modifications arising from age. On the sides 

 of the advancing points of the lobes of the embryo period, 

 which represent a main branch, we see other points gradually 

 appear, which represent the ramifications. Each becomes 

 more and more divided ; the branches become formed ; the 

 ramifications develope themselves ; the foliations of the 

 latter successively appear and multiply, and the simple 

 point of the embryo period is represented, in the adult state, 

 by a large branch, often ornamented by numerous ramifica- 

 tions, and a large number of foliations. It is the same as 

 regards the saddles ; they become more and more subdivided 

 by the auxiUary lobes ; the simple festoon of the embryo 

 state is divided and subdivided, the auxiliary lobes increase 

 and ramify to infinity, and at the adult period, the simple 

 festoon is replaced by a number of foliations, and frequently 

 by the most complicated ornaments. It is remarkal)le, that 



