The Diatoms of Nebraska 43 



so far as noticed, is found near the margin on the same side of all 

 valves of the filament. (Professor Boyer's original description.) 



With crustaceans in surface tow, Devils Lake, N. Dak. 



Family 3. BIDDULPHIACEAE 



" Cells box-shaped, shorter than broad, or but little longer, tran- 

 section circular, polygonal, or commonly elliptical ; valves with two 

 (rarely one) to more poles, each pole with a projection or horn 

 which is shorter than the cell, or when about its length provided 

 with claws; interzones rarely present." 



6. Biddulphia 



Biddulphia Gray in Arrang. Brit. Plants, I, p. 2Q4. 1831. 



Etym., named after a Miss Biddulph. 



" Frustules free or united into filaments, either continuous or in 

 zigzag. Valves elliptic, suborbicular, triangular, quadrangular, 

 etc. ; margins even or undulated, usually more or less inflated in 

 the median portion, rarely depressed, showing elevated obtuse 

 processes at the apices, and having also sometimes horn-like proc- 

 esses. Girdle face more or less quadrangular, showing distinctly 

 processes which are not so visible in the valve face. Connective 

 zone very obvious." 



Biddulphia laevis Ehr. Bcr., p. 122. 1843. 



PI. 22, figs. 811-812. 



" Valve suborbicular or broadly elliptic, bearing near the longi- 

 tudinal axis two spines, opposite, short, obscure, with punctate 

 radiate striae, somewhat undulate as if engine-turned, delicate, 

 about 15 or 16 in 10 /x, intermixed with abbreviated scattered 

 spines. Girdle face with terminal processes, very short, obtuse, 

 truncate, punctate up to the margin. Connecting zone with deli- 

 cate striae, about 16 in 10 yu., punctate in quincunx. Length of 

 valve. 50-120 /A." In our specimens the spines are indistinct or 

 lacking. 



In Middle Loup River at Dunning and Thedford. 



