38 THE DIATOMACE^E OF PHILADELPHIA AND VICINITY 



STRIATELLA UNIPTJNCTATA (LYNG.) AG. 



Frustules with numerous bent septa extending the entire length. Valve lanceolate, 

 somewhat unsymmetrical, subtly punctate, with pseudoraphe quite distinct. 



"The specific name is derived from the appearance of the endochrome which in the 

 living specimen is invariably collected in a central mass with slender threads radiating in 

 all directions toward the cell- wall" (Wm. Sm.). Pyrenoids cuneate, in the centre of the 

 endochrome, numerous. 



Long Island Sound and along the coast. 



PI. 8, Figs. 22 and 23. 



STRIATELLA INTERRUPTA (EHR.) HEIB. 



Frustules quadrangular, with robust alternate septa extending to the middle. Puncta 

 in quincunx, 22 in 10 p. 

 Tessella interrupta Ehr. 

 Very rare along the coast. 

 PI. 8, Fig. 24. (From a form found at Stonington, Conn.) 



ATTHEYA WEST (1860) 

 (named after Thomas Atthey) 



Frustules quadrangular, tabulate, with numerous annuli. Valve elliptical-lanceolate, 

 with a pseudoraphe and a central punctum. Extending from each end is a strong spine 

 half as long as the valve. 



ATTHEYA DECORA WEST 



The only species. Diagnosis of the genus. The valves are imperfectly siliceous, 

 scarcely visible in balsam. 



Very local. Abundant at Shark River, N. J. 

 PI. 8, Fig. 25. 



(6) MEREDIONEjE 



Valve symmetrical in zone and valve view along the sagittal line, but asymmetrical to 

 the transverse axis, cuneate. In zone view sometimes with wedge-shaped septa. Valve 

 finely striated, without central and usually without terminal nodules; a pseudoraphe 

 present. 



Licmophora. Frustules cuneate in stipitate fan-shaped fascicles. 



Meridian. Frustules cuneate in spiral fascicles. 



LICMOPHORA Ac. (1827) 

 (licmos, a fan, and phoreo, I bear) 



Frustules wedge-shaped, joined together into fan-shaped, stipitate fascicles. Valve 

 cuneate, rounded at both ends, septate. Chromatophores granular, round or oval in our 

 species. 



