2l6 



NEW YORK STATE MUSEUM 



ter shale and I.ockport limestone at Lockport (Hall), and probably 

 also at Niagara. 



Orthoceras medullare Hall (i860. Geol. sur. Wis. Reft prog. p. 4) 

 Distinguishing characters. Cylindric, gradually tapering form; 

 septa distant nearly half the diameter; large siphuncle, slightly ex- 

 panded between septa; strong sharp subequal longitudinal striae,, 

 with often alternating finer striae; smooth cast. 



Found in the Clinton limestone lenses in the Rome, Watertowa 



and Ogdensburg railroad section 

 above Lewiston. Rare. The species 

 is normally a western one. 



J^ 



Fig. 148 Cyrtoceras subcancellatum 



A^. Y. 2:290, pi. 61) 



Distinguishing characters. 



Genus cyrtoceras Goldfuss 



[Ety. : xupro?, curved; xipa<^, horn] 



(1837. De la Beche, Handb. d.. 



Geogn. bearb. von v. Dechen. p. 536) 



Shell conic and gently curved, with 

 a depressed elliptic to trigonal cross- 

 section, the aperture in old shells con- 

 tracted to a T-shaped opening; si- 

 phuncle large, eccentric. 



Cyrtoceras subcancellatum Hall 



(Fig. 148). Cyrtoceras (?) 

 cancellatum Hall (1852. Pal. 



Arcuate; transversely oval section; 

 transversely striated surface, and faint longitudinal striae; siphuncle 

 submarginal. 



Found in the '' limestone below the cliff at Niagara Fahs " (Hall). 



Genus gomphoceras Sowerby 



[Ety.: YU(JiJ.(f()^, a pin, bolt, or club; -/Apaq, a horn] 



(1839. Murchison. Silurian system, p. 620) 



Shell straight or curved, pear-shaped, greatest diameter in front 

 of the middle; cross-section circular; mouth contracted, opening by 

 a T-shaped aperture; siphuncle central or eccentric, subcylindric or 

 expanding between the septa (moniliform). 



