vwm Lxxix. 



Orthoceeas sttlds. 



Page 'OS. 

 See Plate 36. 

 Fig. 1. A longitudinal section of epecimen, fig. 2, pi. 36, showing the depth of the air-chambers. No evi- 

 dences of the siphuncle ai-e visible. 

 Fig. 3. Septum^siiowiug the size and position of the siphuncle. 



Obthocebas varum. 



Vago 24». 

 See Plate 112. I 

 Fig. 2. A longitudinal section of a fragment, showing the contour of the chamber of habitation iiml three of 



the air-chambers.  



Fig. 4. An individual preserving a large portion of the grand chamber and ten of the oblique air-chambers. 

 SehoharU, N. Y. 



Obthocebas pbocebus. 



Page 249. 

 See Plate 35, 78 A. 

 Pig. 6, A septate fragment showing the arching, transvei-se stria". 



Fig. 6. A septum of the preceding showing the size and slight excentricity of the siphuncle. 

 Fig. 7. Another fragment, somewhat flattened from compression, retaining the surface ornaments similar to 



the pi-eceding specimen. 

 Fig. 8. An enlargement of a portion of the extei-ior from the side of a specimen, fig. 7. 



Obthocebas pervicax. 



Page 257. 

 Fig. 9. An individual preserving a portion of the chamber of habitation and twenty-two of the air-chambers. 



Lateral view ; one side of the specimen shows a longitudinal canna, indicating the ventral side. 



iSc/ioharie, JV. T. 

 Fig. 10. A septum of the specimen, showing the excentric siphuncle, and its distance from the venti-al mar- 



gin of the septa. 



Orthocebas medium. 



Page SM. 

 Fig. 11. A septate fragment showing the distance between the septa and the carina along the ventral wall?? 



of the chambei-s. 

 Fig. 12. A septum of the preceding specimen showing the size and position of the siphuncle. 



Orthocebas Thoas. 



Page 361. 

 See Plates 41, 78 B, 80, 112. \ 



Fig. 13. A fragment referred to this species principally on account of the distance between the septa. The 

 annulations ai-e more fi-equent than usual, and oblique, while the septa are oblique in the oppo- 

 site direction. This variation is probably due to a natural defoi'mity in the sliell. 



Obthocebas Cbeon. 



Page 260. 



Pig. 14. A view of a specimen, somewhat flattened from compression, preserving four of the air-chambei-s, 

 and a portion of the outer chamber, showing the* fluted ornamentation of the tube made by the 

 elevated, longitudinal stria;. Tlio septal sutures should curve slightly more than is repre- 

 sented. 



Fig. 15. A septum of the preceding showing the size and position of the siphuncle, which has participated 

 in the eflfects of compression. 



