PTEROPOD A 



OF T1IK 



NIAGARA, LOWER AND UPPER HELDERBERG, HAMILTON AND WAVEKLY GROUPS. 

 TENTACULITES, Schlothelm. 1826. 



(See Vol. v, part ii, pp. 155 I 1 



The following .species of this genus are illustrated upon the supplementary 

 plate exiv : 



Tentaculites minutus. 



PLATE CXIV, FIGS. 1,2. 

 Tentaculites minutus, Hall. Pal. N. Y.. vol. 2. p. is;:, plate a 41, fig-. Sa-e. ls.V_\ 



Clinton group. Rochester, Monroe county. 



Tentaculites Niagarensis (Hall), var. Cumberlandle, n. var. 



PLATE CXIV, FIGS ; 6 



This variety differs from T. Niagarensis, Hall (Pal. N. Y., vol. ii, p. 352, pi. 

 lxxxv, figs. 11, 12), in its more conspicuous interstitial annulations and more 

 attenuate form. 



Niagara group. Cumberland, Maryland. 



Tentaculites gyracanthus. 



PLATE CXIV, FIGS. 7-13. 



Echinus gyracanthus, Eaton. Geological Text-hook. 1882. 



Tmiaculites irregularis, Hall. Pal. N. Y., vol. 3, p. 137, pi. vi, figs. 22. 28. 1859. 



Tentaculites gyracanthus, Eaton (Hall). Pal. N. Y., vol. 8. Expl. pi. vi. 



The Tentaculites regtilaris and T. irregularis of Castelnau (Essai sur le Syst. 

 Sil. de l'Amer. Septentrionale, 1843), described as from the Trenton limestone, 

 are probably from the Lower Helderberg group, and identical with this species. 

 (See Pal. N. Y., vol. v, pt. ii, p. 156, foot-note.) 



