P. T. Cleve: The Diatoms of Finland. 65 



T. fenestrata Kiitz. — W. Sm. B. D. XLIII, 317. 



Ab. 36, 44, 45, 46, 47, 48, Sa. 75, Kus. 72, 73, Nyl. 55, Lad. 

 61, 62, 63, 65, 67, 68, 85, Kon. 40, 43, Sb. 4, 6, 8 5 9, 18, 69 

 (var. asterionelloides), 70, 71, Lt. 33. 



Foss. Sa. 88, 89, Ta. 96, Tb. 90, Lk. 104. 



Grrammatophora Ehb. 



G. oceanica Ehb. 



Mb. Al. 56, 58, Sinf. (Dannf.). 



Foss. B. 101, 102, 103. 



The form that occurs in 103 has 29 stria) in 0,0 1 m. m., its 

 valve is 0,0 4 m. m. in length and 0,oo6 m. m. in breadth. It co- 

 mes consequently near to the var. intermedia (Grun. V. H. LIU, 15). 



Cryptoraphideae. 



Chsetoceras Ehb. 



Ch. danicum CI. — Dct videnskablige Utbytte av Kanonbaaden 

 Hauch*s Togter i de danske Have 1889. 



Sinf. Nyl. 76. 



PL III, fig. 18, 19. 



Ch. Wighamii Btw. — M. J. IV, 108; VII, 33. 



Mb. 78, Sinf. 76, Sinb. 80, 81, 82, 84, Ob. 83. 



PI. Ill, fig. 17. 



I have seen only sterile specimens of this species, which 

 occurs in the Baltic from Helsingfors to Tornea. 



Ch. Wighamii in V. H. LXXXII, 1 seems to be the foregoing 

 species, which is quite different. Ch. Wighamii is less siliceous 

 than Ch. danicum and has not such strong awns, which on Ch. 

 danicum are armed with small, spirally arranged spines. The 

 outline of the cells in Ch. Wighamii is in the S. W. lanceolate, 

 but almost orbicular in Ch. danicum. Ch. Wighamii forms 

 long chains, and Ch. danicum occurs in isolated cells or short 

 chains of 2, rarely 3, cells. 



