PLATE LXXXIV. 



OkTBOOERAS SUBUIiATCM. 



Pago 283. 



See Plates S8, 86. 



Fig. 1. A fragment in which the last air-chambers are destroyed by maceration and compression, and the 



action of iron pyrites. This is a common condition with the specimens in the soft shales. 

 Fig. 3. A larger individual in the same condition of preservation as the preceding, retaining the greater 



part of the apical portion. 

 Fig. 4. The apical portion of an example, showing the regular increase in the depth of the air-chambers 



fi-om the apex to the larger extremity. 

 Fig. 6. A fragment of a small individual, presei-\ing the test with its markings over a portion of the tube. 

 Fig. 7. Another individual nearly entire, but somewhat compressed. The exterior test covei's the antexior 



iur-chambers. 

 Fig. 7 + id. A portion of the surface enlarged to show the fine, regular, longitudinal striK, and the moi-e 



irregular lines of growth. 

 Fig. 8. An individual retaining the test over nearly ihe entii-e exterior. 

 Fig. 9. An enlargement of the sui-face of a specimen umila'r to figs 1, 2, showing the fine, irregular, lamel- 



lose lines of growth. 

 Fig. 10. A septum showing the position of the siphuncle. The specimens of this species here represented 



are all fi-om the softer shales of the Hamilton group at Pratt's Falls, Onondaga county, N. T. 



Ohthoceras exile. 



Page 290. 

 See Plates 39, 85. 

 Fig. 8. The chambered portion of a large individual, which has been flattened from compression. Some of 

 the septal sutures are oblique from this cause. The apical portion has been macerated and the 

 characfei-s obliterated in a manner similar to figs. 5, 6, pi. 87. Hamilton gi-oup. Hamburgh, 

 Erie county, N. Y. 



OrTHOCERAS TER8UM. 



Page 286. 



Fig. 5. Dorsal view of a fragment. The other side of the sjiecimen shows the ventral carina along the tube. 



OrTHOCERAS BeBRYX. 



Page 275. , 



See Plates 38, 30, S3. 

 Fig. U. A septum of a small fi-agment referred with doubt to this species, showing the subcentral position 



of the siphuncle. 

 Fig. 12. An outline from another individual, showing the normal, circular, transverse section of the tube. 



York, Livingston county, iV. Y. 



Oethoceras consteictum. 



Page 388. 

 See Plate 85. 

 Fig. 13. A compressed chamber of habitation. The septa marking several air-chambers, composing the 

 lower part of the figure, are not represented. The specimen is covered with a branching para- 

 sitic Bryozoan. 

 Fig, 11. The chamber of habitation of an individual showing a constriction near the middle. 



