THE AERIAL ALGÆ OF ICKLAND 



407 



307, 309 a, 338) in piaces where the presence of abundant 

 organic nourishment is probable, and likewise several times 

 near hot springs (samples 215, 217. 321, 3fi4), but whether 

 these finds give any reliable picture of the life conditions 

 under which it thrives best seems to me doubtful. 



P. molaris shows great resemblance to small forms of 

 P. Brehissonii, but in the latter the striation is strongly di- 

 and convergent, whereas, in the small forms of P. mohtris 

 the striation is almost parallel. Tvvo such small specimens 

 are shown in lig. 26. 



H 



m 



i 



Flg. 26. 



Pinnuhiria 



luoUiris 



(iiiin. 



(X 1200) 



Fig. 27. 



Pinniilaria 

 miiscicola 



n. sp. 

 (X 1200). 



Pinnularia muscicola Boye P. n. sp. 



Valva lineari, levissime capitata, long. 9,5 //, 

 lat. 2,3^*, striis 18 in 10//, parallelis; area apicali angusta. 

 Fig. 27. 



E. Icel. 123. 



This small species I onlj^ found in one of the samj)les 

 liere dealt with, but I also found it in some of the samples of 

 soil which Mr. Mølholm-Hansen brought home to me. This proves 

 that the species occurs on earth in several piaces in Iceland. 



Pinnularia parva (Greg.) Cl. var. Lagerstedtii Cl. f. interrupta n. f. 



A. Schm. Atl. PI. 44, 



fig. 57? 



Fig. nostr. 28. 



Vestmannaeyjar 401. L. 408, 409, 410. 



Pinnularia parva var. Lagerstedtii was first described by Lagerstedt 

 (1873, p. 26, Tab. II, fig. 4) as Xaviciila parimla from Spitzbergen and 

 Beeren Eiland where it was found on »earlh and mos- 

 ses«. Cleve (,Syn. II, p.87) referred it to Pinnularia parva 

 as a variety, and this is no doubt correct. The species 

 P. parva has as a rule the short marginal striæ unintcr- 

 rupted all the way round. but occasionally there occur 

 forms having an interruption in the middle either on 

 one or both sides. Var. Lagerstedtii has likewise as a 

 rule no interruption of the striæ. The specimens found 

 on the Vestmannaeyjar had, however, all such a trans- 

 apical fascia, and I have therefore thought it right to 

 term them f. interrupta. The largest specimens showed 

 transition to the typical P. parva, their apices being 

 slightly capitate (Fig. 28a). Within the f. interrupta may 

 perhaps also be included a »fraglich fonu A. Schm. 

 Atl. 1. c. . On measuring the figure I find the foUowing 

 dimensions: L. 25//, br. 6//, str. 10 in 10/r P parva 

 \ar. Lagerstedtii shows the foUowing range of dimensions: 

 L. 25— 35/(. br. 5-8,8//, str. 8-10 in 10//. Il will thus 

 be seen that the form in A. Schmidt Atl. shows excellent correspondence 

 of dimensions with this variety. Husted t has a figure rei)resenting a 

 form which he calls P. intermedia (1924. Taf 21, fig. 10 , but which cer- 

 tainly cannot belong to this species, but must be callcd P. parva v. Lager- 



27* 



Pinuularia 



pariHi ((irt'}^. Cl. 



var. Laycrstciltii 



Cl. f. interrupta 



n f 



(X 1200). 



