Clarke — The Naples Fauna. 



75 



the original description none bears all of the characters here outlined. 

 Upon a re-examination of the types of this species now in the National 

 Museum, I am convinced that the strong nodation of the inner whorls is not 

 a fascic illation of the concentric striae, though undoubtedly having originated 

 therefrom. Thus Ave may conceive this early nodose condition 

 in J/, nodifer to represent an advance over the corresponding 

 growth stages in J/. fasdoulaUim. We have placed the species Figure si.Mam.ti- 



C0C€7'(tS IX O d if € T 



under the genus Manticoceras because of the form of the shell, Adult suture, 

 notwithstanding the fact that the suture has attained only a gephyroceran 

 stage and is immature or uncompleted with reference to Manticoceras. 

 From the Styliola limestone, (Tenundewa, Canandaigua lake 



Manticoceras Pattersoni, var. stylioprtlum, var. no v. 



Plate VI, Fig. 30. 



This is the characteristic variation of the specific type most abundantly 

 developed in the Styliola limestone It is emphasized by its accelerated 

 phylogerontic final whorl and rapid increase of umbilica- 

 tion on the last volution, an additional gerontic character. 

 The size attained by this form is small. Most of the speci- 

 mens are from the outcrops of Styliola limestone on Canan- 

 daigua lake, and a single representative of the same 

 accelerated type has been found in the Naples fauna. 



Manticoceras sororium, sp. nov. 



Plate IV, Figs. 1-5. 



Of immature examples of this shell Ave have a very 

 considerable number from the Naples strata in the vicinity 

 of Angola, Erie county, though still lacking a satisfactory 

 knowledge of the fully mature shell. The numerous 

 specimens examined do not exceed four volutions nor an 

 extreme diameter of 25 mm., therefore we are not entitled 

 to assume that fully mature shells have yet been met with. 



At the maximum size referred to, the general appear- Fjgure 55 Manticoceras 

 ance of this shell is remarkably like that of Mantic. ZTZmln^oStll 

 jPattersoni in its normal adult state or rather approximates somewhat eni^rged^ 01 ^ 

 the var. styliophilum in which the final conch-section is more narrowed 

 and sagittate. 



