PLATE XXXI. 



TeNTACTJLITES ARENOS0S. 



I'age IM. 

 Fig. 1. An internal cast. 

 Vig. 2. Enlargement of the same. The lower end shows a fragrment of the shell and its relative thickness. 



TkNTACULITES SCALARIPORMIS. 

 Pago 167. 

 Fig. 3. A sjiecimen from cherty limestone of the Upper Helderberg group. 

 Fig. 4. Enlai-gement of the same, showing the form of the annolations ; the surface has obscure encircling 



striff not well indicated on the figui-e. 

 Fig. 6. A specimen which I'etains the shell. 



Fig. 6. Enlargement of the same, showing the annulations and the encircling striK. 

 Fi^. 7. A sjiecimen of somewhat differeut form. 

 Fig. 8. Enlargement of the same. 

 Fig. 9. A fai'ther enlargement, showing the irregularity of the striae and their existence on the annulations 



and in the depressions between. 

 Fig. 10. Enlargement of a specimen which shows an inequality in the strength and distance of the annulations. 

 Fig. 11. Enlargement of a specimen in more compact limestone, having the shell removed by the fracture 



of the rock, and showing its thickness. 



Tentaculites graoilistriatus. 



Page 173. 

 Figs. 12-14. Enlargement (to eight diameters) of three specimens, showing the difference in form and surface 

 characters. See plate :<1 A. 



Tentaculites bellulus. 



Page 169. 

 Fig. 15. A specimen showing the general features of the species. 



Fig. 16. Enlargement of the same, showing the form of the annulations and the encircling strise. 

 Fig. 17. Enlargement of a specimen showing similar features. The shell is broken at a point near the 



middle, showing its thickness. 

 Fig. 18. A furthei- enlargement of the upper portion, showing the more abrupt slope of the annulations on 



the apical side (lower side of tigure). 



Tentaculites attenuatus. 



Page 170. 

 Fig. 19. A gutta-pei-cha impression from a fragment of the rock, showing a group of the shells. 

 Fig. 20. An enlargement of one of the individuals from the same piece of rock. 



Tentaculites spiculus. 



I'age 172. 

 Fig. 21. A gutta-percha impression from a fragment of rock from the Chemung group. Snuthof Ithara, N. Y. 

 Figs. 22, 23. Enlargements "of two indiviiluals fi-om the above specimen. These show a slight difference in 



the form of the annulations. 

 Fig. 2i. A gutta-i)ercha impression from the weathered sni-face of a fragment of rock of the Chemung 



group. Cortland, N. Y. 

 Fig. 25. Enlargement of a specimen, from the same block, which is more slender in form than those on 21, 



but showing similar sui-face characters. 



