PLATE LVII. 



GoMrHOCERAS ? PLANUM. 



rage 3S2. 



Fig. 1. The ventral side of a fragment of the species, carrying seven air-chambers and the base of the 



chamber of hal>itation. 

 Fig-. 2. The convex side of a eeptum, showing the size and position of the siphuncle. liorodhio, Skaiieateles 

 lake, N. Y. 



Nautilus liratus. 



Page 107. 

 See Plate 60. 

 Fig. 3. A lateral view of a partially compressed specimen, which is a caft of the interior, preserving only 

 sti-oug, revolving plications, of which there are nine on the latei-al face of the chamber of 

 habitation. Hamilton group. Quarries north of Slierbume, CkeiMiiyo cvutUy, N. Y. 



Nautilus subliratus. 



Page 409. 



Fig. 4. A dorso-lateral view of a fragment, which pi-eserves the gi-eater part of the chamber of habitation 

 and four of the attached air-chambers. The specimen is a cast of the interior, obliquely com- 

 pre86e(), showing one-half of the doi'sal side and a portion of the lateral face, and preserving 

 five i-evolving plications. 



Fig. 6. The ventral side of the grand chamber, with a few attached air-chambers. The central space ia 

 concave and essentially smooth, while on each side there are six revolving, angular plications. 

 The transverse striiB are partially preserved. 



Fig. 7. The ventral side of the preceding specimen, which preserves the evidence of several air-chambers 

 at the base, the surface being marked by tine, sharply impressed, longitudinal striae, which are 

 cancellated by finer transvei-se striiB ; but without any indication of the revolving i-idges or 

 plications. EarlvUle, Madison county, iV. Y. 



Fig 5. A fragment of the chanibei'ed portion of a Naiitilds, which is refeired with doubt to this si>ecie8. 

 It is much larger than the chambered portion of any other individual which hiis been 

 observed. The radiating plications which are so well defined in this specimen are barely 

 perceptible, or obsolescent on the smaller individuals referred to this species. Hamilton group. 

 Basin Ghilf, 8kaneateles lake, N. Y. 



