220 EitNsr OsTiuii'. 



Synedra affinis Kiil/,., var. siibtilis Gniii., V. II. Syn., Tab. XLI, 

 lig. IS. 



Loc. l):inni:iiks Ihivn (.Mi^a-). 



Synedra affinis Kiilz., var. tabiilald Kiilz., Perag. Mar. D. d. Fr., 

 Tab. LXXX, ligs. 13-14. 



Loc. 0\\ Cape .\nu''lic (.\lj<a>, 2 sampl), Koldewey Isl. (Al}*æ). 

 Synedra affinis Kiilz. var. tabiiUda forma curia acuminata. V. 

 H. Tri.. Tab. X, fig. 431 (Syn. all", labul.). 

 Loc. Oil" Cape Amélie (Algæ). 



Amonjf the numerous scarcely discernable varieties of Synedra affinis 

 only the following are recorded from the Arctic Seas, viz. 

 Synedra all", lanccltiila: \V. (Ireenl. 



— - parva: W. Greenl., East Arct. S. 



- tabui curia aciimin.: (Ireenl., East Arct. S. 



Synedra investiens W. Sm. V. H. Trt., 313, Tab. X, fig. 425. 

 Loc. Off Cape Amelie (Algæ, 5 sampl.), Danmarks Havn (Algæ), Kolde- 

 wey Isl. (Algæ). 



Arct. Distr. W. Greenl., East Arct. S. 



Synedra kamtschatica Griin. Øst. Mar. D. Østg., 450, Tab. VII, 



lig. 85. 



Loc. Oft" Cape Amelie (Algæ, 3 sampl.), Danmarks Havn (Algæ, 3 sampl.), 

 Koldewey Isl. (Algæ, 3 sampl.), Marg. of the Pack-ice (2 sampl.). 



Arct. Distr. Greenl., East Arct. S. 



I have found this species to vary in length from 160 /^ to 260/^. 



Fragilaria Lyngb., 1819. 

 Fragilaria Cylindrus Grun. Grun. Fz. .Is. Ld., 55, Tab. II, fig. 13. 



Loc. Marg. of the Pack-ice (2 sampl.). 



Arct. Distr. W. Greenl., E. of Greenl., East Arct. S. 



Fragilaria islandica Grun., var. hyperborea Cl., Cl. Vega Exp., 

 484. Tab. nost XIII, fig. 25. 



Long. 66/^. Lat. 7 /i. Str. 11 in 10 fi. 



Valva lineare-lanceolata. Striis media in parte valvæ deficien- 

 tibus, ceterum axin apicalem non attingentibus itaqve aream api- 

 calem magnam relinqventibus. 



Loc. Marg. of the Pack-ice (2 sampl.). 



Arct. Distr. According to Cleve: "Greenl., Bessel's Bay." 



This species must undoubtedly be Cleve's Fraçf. isl. hyp. about which 

 he says (1. c): "Area longer, striæ 12 in 0.01 mm." 



Fragilaria striatula Lyngb. V. H. Trt., 324, Tab. XXX, fig. 841. 



Loc. Koldewey Isl. (3 sampl.). 



Arct. Distr. W. Greenl., East Arct. S. 



Plagiogramma Grev., 1859. 

 Plagiogramma Gregorianum. Grev., V. H. Trt., 338, Tab. X, 

 fig. 390. 



