207 



Fig. 231. GoniatiteaunianuuUi ris, anilsutiiiv 

 (after Hall). 



is included a distinct saddle 

 of semi-elliptical form, some- 

 times with a sub-acute 

 apex : ventral lobe narrow- 

 ly triangular, penetrating 

 about one-third the depth of 

 the preceding air chamber. 



Found in the Pleurodic- 

 t} r um beds of Wanakah Cliff 

 (rare). 



The variety obesum, 

 Clarke, characterized by 

 "much greater thickness and tumidity of the whorls," and 

 the variety compression, Clarke, "laterally compressed 

 shells, with a sub-angular periphery," are cited by Clarke 

 from Erie County. (Naples Fauna, p. 116. ) 



The former occurs on the Lake Shore, and the latter in the 

 Hamilton shales, at Wende Station. (See C. E. Beecher, Am. 

 Journ. Sci., Vol. XL., pp. 71-75, PI. I., 1890. ) 



Goxiatites (Torxoceras) bicostatus. Hall. (Fig. 232.) 

 (Pal. N. Y., Vol. Y., Pt. II., p. 450, Pis. LXXIL, LXXIV. 

 Clarke: Naples Fauna, p. 118. ) 



Distinguishing Characters. — Discoidal form of adult: 

 b r o a d 1 y c o n v e x or flat 

 venter ; closed umbilicus 

 (only in last volution); 

 "about the ventral periph- 

 ery runs a pair of low re- 

 volving grooves, one on 

 either side, without which 

 are rather low hyponomic 

 ridges'"; surface ornamen- 

 tation of concentric lines, 

 curving broadly backward over the lateral slopes, sharply 

 forward on the hyponomic grooves, and backward, "in a 

 deep linguiform festoon," on the venter; lateral lobe of 

 suture more prominent and more isolated than in preceding 



Fig. 232. Gonicitites bicostatus. Ventral 

 and lateral views of immature Individuals, 

 Naples shales, Erie Count v, N. Y. (after 



Clarke). 



