Clarke — The Naples Fauna. 



107 



The protoconch is distinctly ornamented nearly to its distal extremity by 

 fine transverse stri;e which have not been followed upon the earlier whorls. 

 The projection of the protoconch is always distinctly shown in the umbilicus 



Figures 79-81. Sandbergeroeerai syngonuin x 25. Figs. 79, 81. Frout and side views of protoconch with 

 first whorl; fig. 79, shows the early septa and the marked lateral protuherance of the protocoucli ; fig. 81. 

 shows the striations on the surface of the protoconch ; fig. 80. represents the protoconch viewed from near its 

 distal extremity, and shows its striated surface. 



of a well preserved shell. In one example some of the septa of the first 

 whorl can be made out and these are seen to have a broad sharp ventral lobe 

 and a low, almost direct lateral curvature which may be traced without modi- 

 fication for about a half volution. 



The whorl section to the completion of the third volution is very broad 

 and narrow, the venter being quite flat. 



The early conditions of the shell are thus seen to be very similar to those 

 of the Styliola limestone species, Jfantic. fuse ioulut inn. 



Although none of the specimens of this rare shell have preserved the 

 adult suture there is little doubt of its being allied to that of Scmdbergei\ 

 Chemungense and Sa ndbei'ger. tuberculosozcostatwfn. The latter is very 

 closely related to this in all other respects, and perhaps a specific differ- 

 ence in the two can be indicated onlv in the strong costation of the earlier 

 whorls in the European species. The presumption, hence, strongly favors 

 the view that Sandberger. syngonwm is the American representative of that 

 specific type. Some of the European costate forms like (toil tuberculatum, 

 Holzapfel,* from the upper Devonian of Westphalia, have a manticoceran 

 suture, but also possess a much more discoidal shell and a narrow hyponomic 

 flattening, resembling our species Mantic. nodifer much more than that under 

 consideration. 



The suture of Sandberger. tuberculoso-costatum is shown in the accompany- 

 ing figure taken from Sandberger. That of Sandberger. Chemungense is an 



* Palaeontographica, xxvii, iii, p. 20, pi. xlv, figs. 7-10. 



