Clarke — The Naples Fauna. 85 



Genus Gephyroceras, Hyatt. 



In discussing the character of the genus Maxticoceras, it has been 

 remarked that there is no real justification for the use of the term 

 Gephyroceras, as its specified type is synonymous w ith the typical example 

 of that genus. It is evident, however, that the author's intention was t<> 

 embrace within this term species like (ion. ccdeulifornvis, Beyr., one of the 

 examples enumerated and w hich is cited by v. ZrrrEL, in illustration of that 

 genus. Gephyroceras seemsto us. toexpressa simple type and a point of depart- 

 ure for the development of more complicated generic forms, and w e apply the 

 term here, perhaps with some lack of precision, to species of this character 

 which do not fit conveniently into other generic groups and at least one of 

 w hich gives a starting point for a series terminating in the highly complicated 

 suture of Beloceeas. Curiously, the items in this series are contemporaneous. 

 The relation of Mantkoceras to these forms, is that of a well established 

 structure derived from the same goniatitine stock, but progressed beyond the 

 gephvroceran stage, for Mantic. JPaMersoni shows clear enough evidence of 

 passing certain features of the gephvroceran condition at a pre-ephebic stage, 

 though at no time in its ontogeny can it properly be called gephvroceran, that is 

 to say, has enough of these features evident at any single stage of its growth. 

 Thus Maxtk ockras stands somewhat apart as a firmly established off-shoot 

 from this stock, and consequently the other members of the Gephyroceras — 

 Belqceras series are separated therefrom by a regularly increasing structural 

 interval. 



Gephyroceras perlatum, Hall (sp. ) 



Goniatites complcmatus, var. perlatus, Hall. Descr. New Species Goniatitidae, 

 p. 1, 1674: Twenty-seventh Ann. Kept. X. V. State Mus. Nat. Hist, 

 p. 132, L87aj Illustr. Devon. Fossils; Cephalopoda, pi. lxx, fig. 12, 1 87 (> ; 

 Palaeontology of New York, vol. v, pt. 2, p. 458, pi. i.xx, fig. 12, 1879. 



An inspection of the figure above cited shows the broadly recurved 

 hyponomic lines indicating a low , convex and obscurely defined keel. The 

 original specimen possesses the form and degree of umbilication characterizing 

 the Gephyroceras — Belqceras series, but there is little that can be made out 

 of its suture, only traces of a small umbilical lobe and a larger saddle being 

 retained. The size of the shell is greater than in any of the allied species of 

 this fauna. A second specimen in the collections of the State Museum 

 is of about the same size as the original and gives a pretty clear conception of 

 the mature suture. This shows a broad ventral saddle, prominent ventro- 



