302 



Fig. 239. Goaiutites 

 sorori um . Young 

 specimen from the 

 Naples shales of Big 

 Sister Creek, Erie Co., 

 N. Y. (after Clarke). 



Distinguishing Clmracters. — Ornamental lines ; these begin 

 in the young shell as strong simple varices, 

 retaining their strength through the third 

 and part of the fourth volution, and be- 

 coming obsolescent on the latter part 

 of the fourth volution; on the ventral 

 side they form a deep and narrow 

 backwai'd loop, curving forward on the 

 hyponomic ridges, and backward with a 

 broad curve on the lateral slopes; the 

 difference in whorl-section is shown by a 

 comparison of the cross-sections (Figs. 240, 238, 236); 

 suture and umbilication as in M. intumescens. 



This species * * "has been found only in the vicinity of 

 Angola, on the Lake Erie Shore, and along Big Sister and 



Farnham creeks, Erie County." 

 (Clarke.) The species occurs in the 

 Naples shales. 



G O N I A T I T E S ( G E 1' H Y R O C E - 



Jixs") HOLZAPFELi. Clarke. (Fig. 

 241.) (Naples Fauna, IGth Ann. 

 Rep't N. Y. State Geol., p. 87, PL 

 VII.) 



Bistinfiiiisliing C 'haracters.— Re- 

 sembles P.lutlierim its compressed, 

 discoidal whorls and flattened, 

 grooved periphery; differs from it 

 in being more widely umbilicated, 

 and in having the lateral saddles 

 Fig. 241. Goniatites hoizapfeii. and sublateral lobes obtuse, a con- 



Copy of Clarke's figure of the type t, • i „ „ w • -i-' ^t +1, ^ ,^^,,, 



specimen, from the Naples shales of dltlOU characteristic Ot the yOUUger 



Eighteen Mile Creek ; suture of one ^ l- T^ 7 ^ 7 



side enlargecKafter Clarke). StagCS OI r. lutlien. 



* GephjToceras, Hyatt, ■• * * includes species with discoidal young whorls, with broad 

 and more or less flattened abdomens in the adolescent stages, and the side divergent as in 

 Manticoceras. * * The adult whorls become compressed and sub-acute in several species, 

 but retain their open umbilici, except in the most involute species. * * The depth of the 

 ventral lobes causes the septa to assume a convex aspect, but the median line remains con- 

 cave until a late stage of growth. The large lateral saddles when first formed, and until a 

 comparatively late stage in radical species, have no corresponding dorsal saddles ; these 

 arise later as" two minute saddles in the dorsal lobe, on either side of the annular lobe." 

 (Hyatt : The Genera of Fossil Cephalopods, p. 316.) 



