PLATE "Lyi-KSIY— Continued. 



I Fig 16. A specimen that has been much compressed and broken in the shale, preserving- the chamber of 

 habitation and several of the air-chambers. 

 Fig. 17. An enlargement of a Bryozoan, encrusting the lower portion of the preceding specimen. The 

 spinules are apparently only the casts of the interior of the cell tubes, the material of the organ- 

 ism having been dissolved. The specimens of this species are all from the coarser shales of 

 the group at Cazenovia, N. Y. 



Okthoceras aulax. 



Page 293. 

 Fig. 18. A fragment showing the prominent, regular transvei-se furrows and ridges. The longitudinal, 

 finer striae are not represented. Hamburgh, Brie county, N. Y. 



Okthoceras scintilla. 



Page 293. 

 8ee Plate 113. 

 Fig. 19. A septate fragment which has been macerated, giving the sutures an undue degree of depression. 

 Fig. 20. An enlargement of three air-chambers of the preceding specimen, showing traces of transverse 



strise. 

 Fig. 21. A longitudinal section of another fragment, cutting the cone on one side of the siphuncle, but not 

 through the axis. Norton's Landing, Cayuga Lake, iV. Y. 



Baotrites olavus. 



Page 31«. 

 See Plate 113. 

 Fig. 16. Lateral view of a specimen preserving a portion of the chamber of habitation and twenty-five air- 

 chambers, and showing an expansion of the tube at the aperture, due to a deposit of iron 

 pyrites. The figure does not fully repi-esent the characters of the species. The chamber of 

 habitation in the specimen figured is somewhat longer than represented. The exposed surface 

 of the tube is flattened from its natural elliptical form, and the suture lines curve forward, 

 and down over the dorsal and ventral sides. Marcellus shales. Schoharie, iV. Y. 



