IP 



PLATE CXII. — Continued. 



Orthoceras oppletum. 



Page ai8. 

 See Plate 81. 

 Fi^ 11. An obliqne view of two air-cban,be,^, showing the raised areola around the siphuncle, with the 

 fun-ows at its margin. p.KHlaced by the solution of the organic deposit, and also the striated 

 surface of the sept*. Schoharie gi-it. Albany county, N. T. 



Orthoceras luxum. 



Page 244. 



See Plates 35, 76, 77, 78, 78 B, 81. 



Fi^ 12 A fragment embracing several air-chamhe.-s. which have been nearly filled with organic deposit. 



F.g. 12. A '-^-'^^^^^ J^ ^^ ^,^ ^^,^^.„,„ ,,„,, ,,, ,,, left by the solution o the n.atena o t e 



depoMt, but in the \^t Mr-chamber the deposit itself i. preserved, as indicated by he small. 



globular m».sses filling the cavity of the chamber. Schoharie gnt Albany c.mv,ty, iY. J. 



Fi^ 13 A weathered fragment, which preserves the furrowed cylinder around the siphuncle, and the pits. 



Hg. 13. ^^'^^^^'^^^J ^^^.^^^ „„ ,^^ ^^,^ ^ p,oduced by the organic deposit. Schoharie gi-it. 



Fi. 14 An fnUr^menf ;/a fragment to two diametei-s. showing the characters of the organic deposit 

 *• mo'faTetlil than is shown in the preceding illuslrarions. The cylinder of the elevated areola 



Ti^und the siphuncle. may be tra.-ed by the in-egular longitudinal furrows, which are a dis tin- 

 K^htg fLtive of t^e a^ola. as it becomes more prominent toward the apex of t e tube . ue 

 S^ he inc'ase in the amount of the deposit. The small pits formed by the solution o he 

 deposit a.^e continued over the entire interior of the air-chambers indicating its exten and the 

 S complete obliteration of the cavities of the air-chambers. Schoharie gnt. Scho- 

 harie, if. T. 



Orthoceras pravum. 



Page 155. 

 See Plates 35, 36. 81. 

 Fi., 15 Ventral view of two air-chambers, showing the obscuration of the ornamentation on the septa, as 

 Fig. 15. >-'™l -;^^; ^„ ,, deposit around the margins of the ai-eola and the ovale 



U^^ expansion, extending over the ventral walls of the air-chambe.-s. On one of the 

 ?ha^™ are shown the i-emains of the concentric stri* surrounding the areolar marking^ 

 The oTrnic deposit consists of coarse, globular masses and a finer deposit over the wall of 

 le Z^hLZl These featu.-es a.^ in.licated, as in the specimens of 0. lu^un. h.r-e illns- 

 IrateX by t^e furrows and small pits made in the foi^ign matter, filling the cavities ot the 

 chambers by the solution of the calcareous deposit. 

 Fig 16. Thetnc^vrsiJe of a septum, showing the lamellose-striate areola around the siphuncle. and its 

 extension to the ventral side. Schoharie giit. Schoharie, N. T. „^ . ^ , . „,,,.„ 



Albany county, N. T. 



m 



