88 Clarence J. Elmore 



PI. II, fig. 401 ; pi. 22, figs. 830-834. 



Rhomboid- or oval-lanceolate, 31-80 /x long, 8-15 /x wide, apices 

 acute or slightly rounded; striations slightly radiate, extending 

 nearly to the raphe, about 24 in 10 /x, composed of rows of dots 

 which also form zigzag longitudinal lines. 



Lakeside, Thedford. 

 Fossil : Agate. 



10. FORMOSAE 



Hyaline space slightly enlarged. 55. A'^. liburnica. 



Hyaline space much enlarged. 56. A'^. arnphisbaciia. 



55. Navicula liburnica Grun. Wien. Verh., 10, p. ^4^, pi. i, fig. 



25. i860. 



PI. II, figs. 402-403. 



Elliptical-lanceolate, 82-100 /a long, 20-25 /"■ wide ; striations radi- 

 ate, interrupted by a sulcus near the margin, extending nearly to 

 the raphe, slightly shorter opposite the central nodule, leaving an 

 oval hyaline space, 12-16 in 10 fx. 



In pool of hot water by old Burlington round house, Lincoln (fig. 402). 

 Fossil: Agate (fig. 403). 



56. Navicula amphisbaena Bory. Encyclop. Method. 1824. 

 PI. II, fig. 404. 



Broadly elliptic, 60-75 /* long, 22-25 /^ wide, apices capitate ; 

 nodules distinct, the central one slightly lateral ; hyaline area very 

 broad, rhomboidal, leaving the striations much shortened ; striations 

 radiate, 12-15 in \o jx, interrupted near the margin by a longi- 

 tudinal sulcus. 



In pool, North Platte ; Benklcman. 



II. LiMOSAE 



A. With a pscudostauros. 57. N. ventricosa. 

 AA. Without pseudostauros. 



h. With three slight inflations. 58. A^. silicula. 



hb. With three large inflations. 59. A^. trinodis. 



^J. Navicula ventricosa Ehr. .//'/;., p. 6y. iS^o. 



PI. IT, figs. 405-418. 



Linear or linear-elliptic, 22-69 /x long, 4-1 i/x wide, apices 



