FRESH-WATER DIATOMS FROM ICELAND 27 



Navicula lyrigera sp. now, Tab. nost. Ill, fig. 38. 



Long: 20//, lat: 11 fi, str. 20 in 10//. 



Valva late lanceolata, apicibus attenuatis. Raphe area hyalina 

 angusta cincta. Striis debilissimis, difficiliter perspiciendis, utroque 

 in latere ita abruptis, ut figura lyræformis, male autem definita, 

 existât. 



Fresh-water sampl. : Grimsey (N.) O. D., Marine sampl.: Skerjafjöröur 

 (S.W.) H. Js., Thörishölmi (S.W.) H. Js. 



This form has some resemblance to Navicula bifissa A. S. in A. S. 

 AU., Tab. CCXII, fig. 33, but it is much more closely striated, and the 

 lateral areas are not so distinctly defined. Nav. biiissa is from Yokohama 

 (therefore probably a marine form). As regards Nav. lyrigera, I have 

 found it in 3 samples, of which one is a fresh -water sample solely 

 containing fresh-water forms; the two others are salt-water samples, both 

 however mixed with fresh- water forms; for this reason I have 

 considered it best placing it as a fresh-water form. 



*Navicula oblonga Ktz. Cl. Syn. II, 21. V. H. Tit., Tab. Ill, fig. 100. 

 Sydri Gardar (SW.) H. Js., Staôasta^ur (S.W.) H. Js. 

 Area: Ubiq. 



Navicula Ostenfeldi sp. now, Tab. nost. Ill, fig. 39. 

 Long: 24 //, lat: 4 //. 



Valva anguste- lanceolata, apicibus capitatis. Raphe media in 

 parte valvæ area hyalina longina cincta. Striis inconspicuis. 

 Krisuvik (S.) C. H. O. 



Navicula peregrina Ehr. Cl. Syn. II, 18. V. H. Tri, Tab. Ill, fig. 101. 

 8 samples (S.W. 6, N. 1, E. 1). 

 Area: Eur., Af., As., Am. 



Var. Menisciilus Schum. Cl. Syn. 1. c. V. H. Trt. 1. c, fig. 103. 

 4 samples (S. 1, S.W. 2, E. 1). 

 Area: Eur., Af., As., Am. 



Var. Meniscus Schum. Cl. Syn. 1. c. V. H. Trt. 1. c, fig. 102. 

 6 samples (S. 1, S.W. 2, N. 2, E. 1). Hot spring: 1. 

 Area: Eur., Af., As., Am., Grl. 



Var. polaris CI. Syn. 1. c. Lgst. Spb., Tab. II, fig. 3. 



Reykholt (S.W. H. Js., Grimsey (N.) O. D. 



Area: Eur., Grl., B. E., Spb. 



In a sample from Hânefsstaôaeyrar (E.) H. Js., I have found a Nav. 

 pereg. with 12 striæ on 10 // being thus more closely striated than the 

 typical form. 



Navicula pinnularioides sp. now, Tab. nost. Ill, fig. 40. 

 Long: 36 u, lat: 6,4 //, str. 8 in 10 //. 



Valva lineari apices rostratos versus attenuata. Raphe area 

 hyalina satis lata cincta. Striis per totam valvam radiantibus, in 



