PLATE II. 
RHYNCHONELLAS OF THE SQUARE LAKE LIMESTONE. 
(Numbers in parentheses refer to catalogue numbers of the specimens figured.) 
Figs. 1, 4, 7. Dorsal, front, and ventral views of R. mainensis, var., with characters 
intermediate between that form and R. mutabilis Hall and R. nucleolata Hall. (M 22.) 
Figs. 2, 5, 8. Dorsal, front, and ventral views of a broad, short beaked form of R. 
mainensis Billings. (M 19.) 
Figs. 3, 6, 9. Dorsal, front, and ventral views of R. nucleolata Hall. (M 23.) 
Figs. 10, 13, 16. Dorsal, front, and ventral views of R. mainerisis, var., approaching 
R. nucleolata Hall. (M 21.) 
Figs. 11, 14, 17. Dorsal, front, and ventral views of a typical form of R. mainensis 
Billings. (M 22.) 
Figs. 12, 15, 18. Dorsal, front, and ventral views of Rhynchonella pyramidal a Hall. 
(M 20.) 
Figs. 19, 20, 21. Dorsal, front, and ventral views of R, nucleolata Hall, of the form 
figured by Billings. (M 23.) 
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