THE CEPHALOPODA 169 



received special names such as Hamites, Scaphites, Turri- 

 lites, and Baculites. Leopold von Buch in 1830 pointed 

 out the importance of the suture-line and separated from 

 Ammonites the Palaeozoic species as Goniatites and the 

 most typical Triassic species as Ceratites. D'Orbigny 

 added several to the list of genera based upon peculiari- 

 ties of coiling. This classification remained unchanged 

 until 1865 : it was inconsistent and lop-sided. Based 

 mainly on coiling a feature that may vary during the 

 life of the individual it yet united under the one name, 

 Ammonites, species with all degrees of involution, 

 from those in which the whorls only just touched to 

 those which were completely involute, yet it separated 

 off under a distinct name those in which the whorls just 

 failed to touch. The number of species of Ammonites 

 too was too enormous, whatever conception might be 

 held of a genus.* 



Von Buch had indeed divided Ammonites into some 

 sixteen groups, but these were based upon external form 

 and ornament only ; while Montfort (1808) and de Haan 

 (1825) had separated off certain groups under distinct 

 generic names, but these had been ignored. In 1865 

 Suess in Europe, and in 1867 Hyatt in America, inde- 

 pendently and almost simultaneously started the sub- 

 division of the genus Ammonites. Their method of work 

 was rather different. Suess (whose work was quickly 

 carried on by Waagen and Neumayr) defined a few large 

 natural groups and gave them generic names. Hyatt, 



* Nevertheless, if used colloquially, the word "ammonite," in 

 the sense of the old generic name, will always remain a useful one 



