Plate LIII ( ontinuerf. 



PAGE. 



Fig. 6. DBYMOTBYPA DICHOTOMA Ulr 399 



6. Section passing through the plane of expansion, x25. It shows the struc- 



ture of the zoarium at different levels, and at the top of the right 



branch, where it is somewhat twisted, the full length of the zorecial 



tubes. 



Trenton limestone. Montreal, Canada. 



Fig. 7. DKYMOTEYPA DIFFUSA Hall 39ft 



7. Transverse section of a branch, x!8, showing row of abortive cells on 



lower side of central lamina, and the distinctly laminated structure of 

 the solid portions of the zoarium. 

 7 a. A tangential section, x!8. 



7 '). Vertical section, x!8, showing thick basal plate, the form of the zouecia 



and the abortive cells. 

 Niagara group, Lockport, N. Y. 



Fig. 8. MITOCLEMA CINCTOSUM Ulr 309 



8. Vertical section of a branch, x!8, showing the long tubular, thinwalled 



zooecia, and three cycles of apertures. 



8 a, 8 l>. Two transverse sections, x!8, the first passing through the stem 

 .n Just beneath, the second just above n ring of apertures. 



Chazy limestone. High Bridge. Ky. 



Fig. 9. DlPLOCLEMA TBENTONENSE Ulr 36!' 



9. Tangential section of a branch, x!8, showing the zooacia cut at varying 



levels between the apertures and the median line. 



i> n, 9 h. 9 c. Three transverse sections, x!8, showing the'comprcssed form of 

 the branches, and slight modifications in structiiii'. 

 Trenton group. Trenton Falls. N. Y. 

 .tut'.'. 



Fig. 10. DlPLOCLEMA 8PAESUM Hall 369 



Tangential section. x!8, showing structure similar to lower half of tic. 9. 

 Niagara group, Lockport, N. Y. 



Fig. 11. PBOTOCBISINA EXKIUA Ulr. (See also PI. XXIX.) 405 



11. A deep tangential section ,x!8, showing the tubes that open on the side 



of the branches throughout their length. 

 11 a. Portion of same section where it passes just beneath the mouths of 



the dorsal rows of cells, x!8. 

 11 6. Vertical section, x!8. 

 11 c. The same kind of section as fig. 11, taken from Trenton Falls, N. Y. 



specimen, in which the zotuoia are a little shorter than usual. 

 11 d, 11 e. Two transverse sections, x!8, showing the four ranges of zooecia, 



and the thick outer walls. 



Trenton limestone, Montreal, Canada, and Trenton Falls, N. Y. 

 rfj cd i 



Irtlllt yAt Inn; 



ufliX 



