294 



EPITHEMIA. 



GENUS 35. EPITHEMIA 

 BREB., 1838. 



Valves arcuate, furnished inter- 

 nally with robust costae, and exter- 

 nally with moniliform striae, without 

 nodules. Girdle face linear, more or 

 less inflated in the central portion. 

 Frustules parasitic on other plants. 

 Endochrome as in the Amphora. 



Fig. 66. Epithemia turgida. 



a Girdle view. 

 b Valve view. 



Two rows of 



beads 



between two 



consecutive 



costas. 



[ f 



Costas 

 and 

 striae all j 

 radiant. 



ANALYSIS OF SPECIES. 



' Apices ( 

 more or 1 Valves very arcuate . E. turgida. 

 Beads less \ 



very -| rostrate [ Valves slightly arcuate . E. granulata. 

 robust, j capitate. ^ 



. E. Hyndmanni. 



E. Sorex. 

 . E. gibba. 



[ Apices very obtuse 



i 



L Beads very fine and very approximate 



I Costae and striae parallel, except at apex of valve 



At least four 



rows of beads 



between two 



consecutive 



costae. 



( { Costae with apices capitate in gir- 



I Costae scarcely ra- | die view . E. Argus. 



diant, beads rather -; 



robust . . I Costae with apices not capitate in 



girdle view . E. Zebra. 



( Frustules almost circular ; valves 



semi-circular . . E. Musculus. 



Costae very radiant, | 



beads very fine . , Frustu]es elliptic . valves semi-lan- 



[. ceolate E. gibberula. 



* Two rows of beads between two consecutive costa. 

 a. Beads very robust. 



E. turgida (Ehr.) Kutz. (Bac, pi. 5, f. 14 ; H.V.H. Atl, pi. 31, 

 f. 1 and 2* ; Type No. 251), plate 9, fig. 346. 



Valve arcuate, with apices more or less rostrate capitate ; dorsal margin 

 rather flexed; ventral margin slightly flexed; costae radiant, about 4 in 1 



