PALEONTOLOGY. 

 PLATE XV. 



Page. 

 Heteroceras newtoni WLitf 449 



Figs. 1, 2. Views of the opposite sides of the type specimen, sliowing the rapidly expand- 

 ing tul)e, and jjrescrving tlic surface characters. 

 Fio. ;!. Vertical view of tin- sanx' individual, showing the broad umbilical opening and the 



commencement nf the dellcction of the outer end. 

 Via. 4. Diagram of a septum from near the larger extremity of the specimen. Enlarged 



to two diameters. 



Ancyloceras jexxevi Whitf 452 



FIg. .'). Enlargement, to one and a half diameters, of a septum from a small fragment of a 

 Hpecimen, showing some variations as compared with that shown on Plate 16, 

 Fig. 9 See also PI. IG, Figs. 7-9. 



Hktkrockr.v.s f nebuascex.si: M. <fc H 451 



Fig. 6. Lateral view of a specimen referred to this species, showing two volutions of the 

 septate shell. See also PI. 14,'Fig. 9. 



ANCi'LOCERAS TRICOSTATUS Whitf 454 



Fig. 7. Lateral view of the fragment, showing the triplicat'C character of the costjB, and 



the obtusely triangular nodes on the dorsum. 

 Fig. 8. Enlarged diagram of a septtim from near the commencement of the outer third of 



the fragment. Two diameters. 



M 



