Plate LXIII Continued. 



. PAGE. 



Fig. 6. ARCHIMEDES OWENANUS Hall 570 



6. Fragment of the axis showing usual form and size. 



Keokuk, Iowa. 



Illinois State Museum. 

 6 a. Strongest fragment seen, natural size. 



Keokuk group, 3 miles n. e. of Quincy. 111. 



Illinois State Museum. 

 6 b. Vertical section of large axis, natural size. 



6 e. Vertical section of slender axis, natural size, forming unusually long 



volutions. 



Fig. 7. ABCHIMEDES NEGLIOENS Ulr 569 



7. Axis of this species, natural size. 



Keokuk, Iowa. 

 Illinois State Museum. 



7 o. Vertical section of another example, natural size. 



Fig. 8. ARCHIMEDES WOBTHENI Hall , 571 



8. Axis of this species, showing the usual peculiarities. Natural size. 



8 . Vertical section of portion of same, natural size. 



Warsaw, III. 



Illinois State Museum. 



Fig. 9. ABCHIMEDES DISTANB Ulr 578 



9. ! a. Two fragments of the axis of this species, natural size. 



The first from Sloan's Valley, Ky., the second from Litchfleld, Ky. 

 E. 0. Ulrich's collection. 



9 6. Specimen from Chester, 111., showing the axis with much of the fenes- 



trated expansion. At the lower edge of the latter a new axis is being 

 formed, which, as Is invariably the case, turns in the opposite direc- 

 tion. 

 Illinois State Museum. 



Fig. 10. ABCHIMEDES OBANDIS Ulr 569 



Vertical section of a small specimen of this species, natural size. 

 Compare with flgs. 6 b and 8 a. 

 Illinois State Museum. 



Fig. 11, 11 b. ABCHIMEDES PBOUTANUS var , 576 



11. Specimen with much of the fenestrated expansion. Natural size. 



Chester, 111. 



Illinois State Museum. 

 11 l>. Natural size view of axis from Sloan's Valley, Ky. 



E. O. Ulrich's collection. 



These two specimens differ from A. proutanus, chiefly, in forming 



longer volutions. 



Fig. 11 a, 11 c, 11 d. ABCHIMEDES INVAGINATUS Ulr 575 



11 a. A strong axis of this species, natural size. 

 Chester, 111. 

 Illinois State Museum. 

 11 c, 11 d. Vertical sections of two specimens showing extremes in volutions. 



