256 JAMES PEER IN SMITH AND STUART WELLER 



and has caused much fruitful discussion. The main points for 

 which they contended have been accepted, and now it is gener- 

 ally admitted that ammonite genera may be much more closely 

 related to goniatites than they are to contemporaneous or even 

 antecedent ammonites. Karpinsky's 1 masterly researches in the 

 phylogeny of the Prolecanitidae contributed largely to this 

 result, and prepared the way for Haug's 2 exhaustive study of the 

 relations of the various phyla of goniatites. 



When it is once admitted that there are several distinct stocks 

 of different degrees of specialization and developing in different 

 directions, there is no longer any sound reason for the com- 

 monly accepted opinion that they all made the transition at the 

 same time ; indeed, it is extremely illogical to expect that this 

 would be the case. In spite of this, it will cause surprise, 

 especially among those that cling to time-honored criteria, when 

 it is announced that not only are characteristic ammonites found 

 below the Permian, but even at the very base of the Carbonif- 

 erous system, and in such an advanced stage of development 

 that the transition from goniatite to ammonite must have taken 

 place already in the Devonian. The occurrence of these forms 

 is authentic, and not sporadic, for they were found in the same 

 horizon, and in the same faunal association in three widely sepa- 

 rated localities in America. It may be that they were prema- 

 turely specialized forms, like Clymenia, that developed suddenly 

 from the main, unspecialized stock, and as suddenly became 

 extinguished ; but the existence of similar and evidently closely 

 related forms in the Trias presupposes continuance of the stock. 

 In reality, our knowledge of the various families of Paleozoic 

 animals is as yet only fragmentary, and lack of record is no very 

 strong argument against the occurrence of any group. We must 

 remember that the greater part of the Paleozoic deposits are not 

 now open to our inspection, and that whole faunal provinces and 



1 Die Ammoneen der Artinsk-Stufe. Mem. Acad. Imper. Sci. St. Petersburg, 

 seventh series, Tome XXXVII, No. 2, 1889. 



2 Etudes sur les Goniatites. Mem Soc. Geol. France, PaleontoL, Tome VII, No. 

 18, 1898. 



