PLATE LXXXIl. 



Orthoceras crotalum. 



« 

 l-nsro iSS. 



See Plates 42. 113. 



Fig. 1. An imperfect sivjoimen, showiiifr the characters of the tube at the aperture, and the surface-niark- 



ingn of tlie shell. Pratt's Fhlls, Onondaga county, N. Y. 

 Fijr. 2. A frapraeiit with the annulations somewhat irregular in frequency. The tube has a slig^bt eui-va- 



ture, either natui-al or from compresfion. Delphi, iV. 1'. 

 TPig. 3. A email, slightly compressed specimen, showing the surface ornaments, and the increase in the 



pi-ominence of the annulations toward the larger extremity. Eajit shore of Cayuga Lake, N. Y. 

 Fig. 4. A lateral view of the same, showing a curvature of the tube near the apex. 



Fig. 5. Thelnitial extremity, showing the incipient annulations of the apex. EastslunreofCayuga IxiJie, N. Y. 

 Fig. 6. The apical portion of an individual, showing moi-e satisfactonly the increase in the prominence of 



the annulations, and the gradual change in their frequency toward the chamber of habitation. 



East shore of Cayuga Lake, N. Y. 



Orthoceras .^oea. 



Page 295. 

 Fig. 7. A fragment of the chambered portion, showing the annulations and surface-markings of the shell. 

 Fig. 8. A septum of the preceding, showing the central position of the siphuiicle. 

 Fig. 9. A fragment of the internal mould. The furrows in this example are nearly the reveree of the 



exterior surface, as shown on other specimens. Pratt's Jnill,<t, Onondaga county, iV. Y. 

 Fig. 10. A small fi-agment pi-eserving the surface ornamentation. Geneseo, Lki'mgstmi county, N. Y. 

 Fig. 11. A portion, apparently, of the chamber of habitation, showing the low, transverse undulations, and 



the strong longitudinal ridges with smaller intermediate ridges and strise. &eneseo, Livingston 



county, N. Y. ' 



Fig. 12. A fragment of a large individual, similar to the preceding, showing the low undulations of the 



tube. In the calcareous beds of the Hamilton group in Madison county, N. Y. 

 Fig. 13. A septum of the same, showing the position of the siph uncle. 



Orthoceras ndntium. 



Page 299. 

 Figs. 14, 16. Longitudinal sections of specimens firmly imbedded in the suri-ounding rock, and not furnishing 

 sufficient data for positive determination. The specimens are referred to this species on 

 account of their association.. Pratt's Falls, Onondaga comity, JV. Y. 



Orthoceras csilamen. 



Page 298. 

 See Plates 42, 43, 118. 

 Fig. 16. A portion of the test enlarged, from specimen fig. 10, pi. 42, showing the characteristic rounded, 

 intei-rupted, longitudinal strise, crossed by finer striie and broad, lamellose lines of growth. 

 Ontario county, N. Y. 



Orthoceras (Edipus. 



Page 294. 

 See Plate 37. 

 Fig. 17. A crushed fragment of the chamber of habitation and several attached air-chambers, preserving 

 portions of the test, and showing on the internal mould the strong longitudinal ridges. Oeneseo, 

 Livingston county, N. Y. 



Orthoceras Thestor. 



Page 302. 

 Fig. 18. A fragment, with the upper portion of the tube flattened from compression, and partially covered 

 with the adhering shell. The figure shows the very numerous, regular annulations of the tube. 

 Harcellus shale. Scluiharie, N. Y. 



