64 Clarence J. Elmore 



ee. Striations lacking in the middle. 



6. N. intermedia, 

 cc. Costae finer. 



d. Not inflated in the middle or onl}' slightly so. 

 e. Apices not rostrate-capitate. 



/. Apices neither inflated nor attenuate. 



7. N. stauroneiformis. 

 ff. Apices somewhat attenuate. 



g. Costae delicate. 8. A'', hrchissonii. 



gg. Costae heavier. 9. A^. rangoonensis. 



fff. Apices inflated. 



g. Slightly or not at all inflated in the middle. 



10. A'^. parva. 

 gg. More inflated in the middle. 



11. N. decurrcns. 

 ee. Apices rostrate-capitate. 



/. Costae distant. 12. N. subcapitaia. 



ff. Costae closer. 13. N. appendiculata. 



dd. Inflated in the middle. 14. A'', braimii. 



bb. Constricted in the middle or undulate. 

 c. Apices strongly rostrate-capitate. 



d. Swollen in the middle. 15. A'', mesolepta. 



dd. Constricted* in the middle. 16. N. thermes. 



cc. Apices slightly rostrate. 



d. Striations strongly radiate. 17. A'', legumen. 



dd. Striations slightly radiate. 18. A^. nodosa, 



ccc. Apices rounded or slightly con.stricted. 



19. N . acrospliaeria. 



1. Navicula nobilis (Ehr.) Kiitz. Bacill., p. p8, pi. 4, fig. 24. 



1844. 



Pinnitlaria nobilis Ehr. Ahh., p. 20. 1840. 



PI. 6, figs. 178-182. 



Linear-elliptic, slightly swollen in the middle and at the ends. 

 127-400 /x long, 16-50 /x wide; costae heavy, 4-8 in 10 /a, radiating 

 in the middle, then parallel, and slightly converging at the ends, 

 shortened, leaving a hyaline area along the raphe about one-third 

 the width of the valve. 



With luxuriantly-growing algae in rivers, etc. : Clear Lake, Crete. 

 Fossil : Cherry County, Mullen. 



2. Navicula major Kiitz. Bacill., p. gy, pi. 4, fig. 19. 1844. 

 Pinnularia major Rabenh. Si'issw. Dial., p. 42, pi. 6, fig. 5. 



1853- 



