Plate XVII. 



Page 

 Fig. I. Desmacella ha^jztfera n. sp. a styli, b developmental forms, c irregular styli from 

 the basal layer, x 77, d sigmata of the large form, e sigmadrama, f develop- 

 mental form of the large sigma, g sigmata of the small form, x 485, h rha- 

 phides of the long form, single and as trichodragma, i rhaphides of the short 

 form, single and as trichodragmata, x 380, k commata, X' 700, / gemmiila?, 

 X 255, silicious globules, x 4S5 93 



— 2. Desmacella groenlandica Frstdt. a styli, b irregular styli from the basal laj-er, 



X 77, c sigmata of the large form, x 485, d sigmata of the small form, x 700, 

 e rhaphides of the long form, single and as trichodragma, f rhaphides of the 

 short form, single and as trichodragma, x 255, g commata, x 700, h gemmula?, 

 X 255, silicious globules, x 485 (gemmula is drawn from the original specimen 

 of Fristedt) 95 



— 3. Bieinma annexa O. S. a tylostyli and subtylost\li , b a developmental form, 



X 120, c head ends of different needles, x 380, d toxa, x 485, e sigmata of 

 the larger form, f sigmata of the smaller form, x 485 85 



