Clarke — The Naples Fauna. 4."> 



the precise value of corresponding deviations in the European expressions 

 estimated with reference to local conditions, obstructed or accelerated develop 

 ment, can not be satisfactorily attempted in this connection. 



The Generic Designation. The old genus Goniatites w as long ago con- 

 ceded to l>e insufficiently precise as a generic designation. That it is 

 still in vogue as a general application is due both to its great usefulness 

 as a broad distinction from forms of similar aspect grouped tog-ether under 

 such names as Ammonites, Ceratites, etc.. the imperfection or incompleteness 

 of its subdivisions and the impossibility of always recognizing full and precise 

 generic characters in given material. 



The old division has been resolved into many parts by recent writers and 

 no doubt the many subdivisions which have been introduced will be found 

 distinctions of precise r value and the term Goniatites itself become restricted 

 to the division containing the species upon which it was established (Glyph- 

 ioceras, Hyatt). 



Students of the goniatites have made their various generic distinctions 

 Dot always from the same point of view, but it may be said that the propo- 

 sitions of Hyatt, especially, and of v. Mojsisovics, Waagen and Karpensky 

 were based not upon any single set of structural characters and variations ; 

 rather upon differences pervading the entire shell. 



Professor Hyatt introduced the term Manticoceras (1884) for goniatites 

 " with compressed and often very involute whorls, which are, however, directly 

 traceable by the closest gradations into forms with broad whorls, open um- 

 bilici and an aspect similar to that of Anarcestes. The young are invariably 

 less discoidal than in GepbyroCERAS, the abdomens rounded and the sides 

 divergent outwardly. A close roemblance to Agoniatites btcanaliculatiis or 

 tubet'culoso-costatus occurs in the costated young and in the sutures and form 

 of Mont, tri/partitwm until a late larval stage. The adult sutures have the 

 same general aspect as those of Gephyroceras, but the septa in the compressed 

 involute forms become more decidedly convex. The lobes remain rounded 

 until later stages of growth, the funnel lobes are generally smaller, the larger 

 lateral saddles are more persistent and retain their forms unchanged even in 

 the extreme old stages of the largest specimens. 11 " The type of this genus is 

 pronounced to be Goniatites simulator. Hall, a form from the hiorTiywJms- 

 bearing beds containing the commingled Naples and Otselic fauna near or at 

 Ithaca, X. Y. This species (or rather, specimen, for but the single example to 

 which the specific name was originally applied has come within our knowledge) 

 is pretty correctly figured in the Palaeontology of New York, vol. v, pt. 2 (pi. 



* Proc. Boston Soc. Nat. Hist., vol. 22, p. 317. 



