Bull. U. S. B. F., 1926. (Doc. 1007.) 
Figs. 7-12. — Development of the egg of the white sucker, Calostomus commcrsonii. In each case the shell has 
been removed. 7. At 40 hours (from egg cleared in xylol). 8. Extent of the blastoderm at 54 hours. 9. Com- 
plete investment of egg at 92 hours. 10. Dorsal ridge and head process at 149 hours. 11. Development of the 
brain as seen at 174 hours. 12. The same at 192 hours (S days) 
