PLATE LXXXIV— Continued. 
A specimen that has been much compressed and broken in the shale, preserving the chamber of 
habitation and several of the air-chambers. 
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. 
Orthoceras aulax. 
Page 293. 
Fig. 18. A fragment showing the prominent, regular transverse furrows and ridges. The longitudinal, 
finer striae are not represented. Hamburgh, Erie county, N. Y. 
Orthoceras scintilla. 
Page 293. 
See 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 
i striae. 
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, N. Y. 
Bactrites clavus. 
Page 316. 
See Plate 113. 
Fig. 15. 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 represent the characters of the species. The chamber of 
habitation in the specimen figured is somewhat longer than represented. The exposed surface 
of jthe 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, N. Y. 
Fig 16. 
Fig. 17. 
