366 DESCRIPTION OF \^Polygastrica. 



ated, sti-aight, and acute ; margin very finely striated ; central space 

 smooth. Diameter 1 -432nd. Eichmond, Virginia. 



Feagilaeia Amphiceros. — This species -was described in 1843, by 

 Ehrenberg, as a doubtful Fragilaria, and as equal to a Cocconeis de- 

 prived of its central foramen. His latest description is : Testule 

 narrowly linear, rather turgid in the middle ; apices much attenuated, 

 but truncate ; surface remarkable by its transverse strise throughout. 

 It differs from EJiaphoneis by the want of a median longitudinal band. 



F. Bacillum. — Smooth, laterally linear, rounded at each end ; five 

 to six times longer than broad. Length 1- 720th. Oran, Africa. 



F. striolata (1844) ;= F. pinnata. 



F. nodidma. — Linear, twelve times longer than broad ; striated 

 transversely; stiiae eighteen in l-1200th; narrowly linear laterally, 

 constricted below the apices, marked by narrow rows of nodules. 

 Length l-648th. Kurdistan. Transverse striae (nodules) of the 

 sides eighteen in 1-1 152nd. 



F. hirostris. — Very small, suddenly attenuated at the acute ex- 

 tremities, laterally lanceolate. Has nearly the characters of a 

 Staurosira (l-3120th.) 



F. granulata. — ^Habit of F. Amphiceros, but stouter, tapering to- 

 wards the ends ; pirmules disposecf^i bundles, and granular. (l-720th.) 



F. pinnulata. — Bacillar, equal throughout, often five to six times 

 longer than broad ; laterally rounded at each end, not attenuate ; 

 pinnules twenty-five in l-1200th. (l-1152nd.) 



F. rotundata. — Bacillar, equal throughout j length often nine 

 times greater than breadth ; laterally rounded, not contracted at the 

 two extremities; twenty strong pinnule? i i l-1200th. Length l-480th. 



F. 2whjedra. — Oblong, angular (hexangular ?) bacillar ; length three 

 times greater than width ; transverse striae (pinnules) delicate. 

 Length 1 -900th. Fossil at Norwich. Connecticut. Allied to F. 

 Bacillum. 



F. (?) mesotyla. — Bacillar, tiirgid at the centre, ends obtuse, ti'ans- 

 versely striated, striae granular. Longth 1 -480th. Very like Staur- 

 optera granulata, but wants the longitudinal band and crucial um- 

 bilicus. 



F, (?) Stylus. — Fossil, discovered by Ehrenberg in marl from 

 JEgina. 



