OF DENISON UNIVERSITY. 
1^5 
Diafomos, a through-cutting), which takes place, not transversely, but 
longitudinally; and the lines which mark its progress are almost al- 
ways visible in them. In this process of division new valves are 
formed along the line of division, the old ones remaining on the outer 
sides, and each new diatom cell having an old valve and a new one. 
But sexual reproduction takes place by conjugation and by the forma- 
tion of auxospores, which restores periodically the normal size of the 
species. 
Diatoms are quite abundant in the vicinity of Granville, Ohio, 
some of them being rare specimens. The following list I have iden- 
tified for the most part, by recourse to the photographic plates from 
Aldolf Schmidt’s “Atlas der Diatomaecen-Kunde.” 
CymbellcB gastroides, K. 
Naviciila polystricfa, Gru. 
Navicula polystricta, (var. ) circumstricta, Grunow. 
Naviciila sentelioides, Sm. Domb. 
Naviciila Cynthia, A. S. Java. 
Naviciila cnspidata. f 
Navicula borealis.X 
Navicula crypto cephala. J 
Naviciila entomon.X E. 
Navicula biceps. E. 
Navicula latissima, Greg.J 
Navicula consimilis, A. S. 
Navicula lanceolata, K. 
Navicula brevis, Greg. 
Navicula latissima, (type), A. S. 
Navicula longa, Greg. 
Nitzs cilia coaretala. J 
Pleurosigma Spenceri, J. 
Gomphonema acuminatum, E. 
Fragilaria lanceolata. J. 
Diatoma meridian -circulare. J 
Friceratiiim solenoceros, E. 
Friceratium Jensenianum, Grunow. 
Friceratium venosum, Brighton. 
f. Not typical, but probably a variety. 
Identified by plates in Indiana Geol. Rep. Vol. II 
