83 



37a Valves with numerous internal transverse ribs extending 



completely across the valve 38 



37b Valves without internal transverse ribs. 



ko 



38a Raphe and axial area with "V"-shaped medial extension; with 

 transverse septae appearing as costae and alternating with 

 two or more rows of punctae - EPITHEMIA 



Fig. 131. Epithemia sorex , (12), cells 20-65u long, 8-15H wide; 

 5-7 septae in lOu; 12-15 punctae rows in 10n. X 1000. 



valve view 

 Notes : 



girdle view 



Fig. 132. Epithemia turgida , (12), cells 60-220u long, 15-10u wide; 

 3-5 septae in lOu, 7-9 punctate rows in 10u. X 1000. 



valve view 



girdle view 



Notes: 



