MARINE DIATOMS FROM THE COASTS OF ICELAND 375 



Thalassiosira Cl. 1872. Gr. N. P., 16. 



Thalassiosira gravida Cl. Gr. N. P., 18, fig. 12; spore, A. S. Atl., 

 Tab. LVIII, fig. 44 (Coscinodiscus subglobosus). 



7 samples (all S.W. . H. Js., Grid., C. H. O. 

 Area: Eur., Am., Grl., A. S. 



Only spores have been found. 



Melosira Agardh 1824. V. H. Trt. 438. 



Melosira nummuloides (Bory) Ag. V. H.Trt. 440, Tab. XVIII, fig. 608. 



26 samples (S. 3, S.W. 9, X. W. 4, N. 7, E. 3). 

 Area : Ubiquist, Grl., A. S. 



Melosira sulcata (Ehr.) Ktz. V. H. Trt., 444, Tab. XIX, fig. 624. 



81 samples S. 5, S.W. 61, X.W. 9, X. 6). 

 Area : Eur., Afr., As., Am., Grl., A. S. 



Melosira sulcata 1'. radiata. Grun. Fz. J. L., 42, Tab. V, fig. 35. 



8 samples (S.W. 6, X.W. 1, X. 1 . 

 Area: Eur., A. S. 



Podosira Ehr. 1840. V. H. Trt., 447. 



Podosira hormoides (Mont.) Cl. & Gr. A. D., 118; A. S. N. S. D., 

 Tab. Ill, fig. 40. 



156 samples (S. 24, S.W. 79. X.W. 19, X. 17, E. 14, S. L. 3). 

 Area: Eur., Am., Grl. 



In several of the samples examined by me Podos. horm. occurs 

 with a diameter of up to 70 u and of a verv fine structure. For this 



/ * 



reason it ma\ r perhaps be considered as a forma major of Podos. horm. 

 var. glacialis Grun., see Fz. J. L., 56, tab. V, fig. 32. I have found it with 

 the more distinct punctuations indicated in the figure, as well as without 

 these. 



Hyalodiscus Ehr. 1854. V. H. Trt.., 448. 



Hyalodiscus subtilis Bail. Per. D. mar., 443, Tab. CXIX, fig. 7. 



7 samples (S.W.I, X. 3, E. 3). 

 Area: Eur., Afr., As., Am., Grl., A. S. 



Hyalodiscus subtilis Bail. var. scoticus (Ktz.) Grun. Per. 1. c. 443, 

 Tab. 1. c., fig. 8. 



209 samples (S. 28, S.W. 110, X.W. 24, X. 39, E. 7, S.L.I). 

 Area: Eur., Am., Aust., Grl., A. S. 



Isthmia Ag. 1830. Per. D. mar., 375. 



Isthmia nervosa Ktz. Per. D. mar., 375, Tab. XCI. 



64 samples (S. 20, S.W. 24, X.W. 3, X. 7, E. 7, S. L. 3). 

 Area: Eur., Am., Grl., A. S. 



