THE MICROSCOPE IN HISTOLOGY AND BOTANY. 145 



31. Raphoneis. Doryphora without a stalk. 



COHORT 6. AMPHIPLEURE^E. Fr. free, single, straight, 

 or slightly sis;moid ; v. lanceolate, or linear-lanceolate-, 

 with a median longitudinal line. 



32. Amphi pleura. Characters as above. 



ft Valves with a Median Nodule. 



COHORT 7. COCCONEID.E. Fr. straight or bent, attached 

 by the end or side; v. elliptical, equilateral. 



33. Cocconeis. Fr. single, compressed, adnate; v. ellip- 

 tical, one of them with a median line. 



COHORT 8. ACHNANTHE.E. Fr. compressed, single, or 

 rarely united into a straight filament, curved, attached 

 by a stalk at one angle; uppermost v. with a longitudinal 

 median line, lower v. the same, and a stauros or transverse 

 line; marine. 



35. Achnanthidium. Fr. those of Achnanthes, but free; 

 aquatic. 



36. Cymbosira. Fr. as Achnanthes, solitary or binate, 

 stipitate, and attached end to end ; marine. 



COHORT 9. CYMBELLE^:. Fr. straight or curved, free or 

 stalked at the end ; v. inequilateral, not sigmoid. 



37. Cymbella. Fr. free, solitary; v. navicular, with a 

 subcentral and two terminal nodules, and a subrnedian 

 longitudinal line; aquatic. 



38. Cocconema. Fr. as Cymbella, but stalked; aquatic. 

 COHORT 10. GOMPHONEME^I. Fr. wedge-shaped, straight, 



free, or stalked ; v equilateral. 



39. Gomphonema. Fr. single or binate, wedge-shaped, 

 attached by their ends to a stalk; v. with a median line, 

 and a median and terminal nodules; aquatic. 



40. 8phenella. Fr. free, solitary, wedge-shaped, invo- 

 lute; aquatic. 



10 



