NAPLES FAUNA IN WESTERN NEW YORK, PART 2 379 



feature than that specified, these three terms, intumescens, patter- 

 soni and rhynchosto m a, express distinct paraphases of the specific 

 type. [See table of paraphases of Manticoceras expressed in terms of M. 

 pattersoni, pt i of this work, p. 83.] 



Manticoceras ammon Keyserling is confessedly a very close ally 

 of M. intumescens. Study of the figures and description given by 

 Holzapfel impresses me with the striking agreement in essential differentials 

 with the typical M. pattersoni, an agreement seen not alone in the 

 evolution of the contour, but also in the progressive development of the 

 sculpture from early stages onward. I think we may fairly conclude that in 

 both the New York and the Timan faunas the two types are present, and 

 that these two stand for each fauna, in essentially the same relations to each 

 other. 



In Manticoceras backlundi we have a broad backed shell with 

 lateral pilae highly developed, an expression for which we find no precise 

 equivalent in the Naples fauna. 



It is remarked by Holzapfel that this genus is not as abundantly devel- 

 oped in individuals in the Domanik as in the Naples fauna, and it is a nat- 

 ural consequence that the variety of expression is less. But in the Naples 

 fauna the minor expressions of the genus are relatively of less common 

 occurrence. 



Gephyroceras. We have noted in part 1 that this name, so far as 

 dependent on its type species, is actually synonymous with Manticoceras, 

 but have employed it for flat, discoid, widely umbilicated shells having a 

 suture differing from that of Manticoceras in degree rather than kind, the 

 lobes and saddles being equivalent in adulthood to an immature condition 

 in Manticoceras. The name as it now stands is not grounded on any speci- 

 fied type and hence is of itself of unsubstantial value, but it has been 

 employed by both Holzapfel and the writer with application to essentially 

 the same group of forms. 



In the Naples fauna the shells that could be referred to Gephyroceras 

 are relatively few, but they share with Probeloceras lutheri and 



