No. 3] REMARKS ON NORTHERN LITHOTHAMNIA. 15 



formations of tissue. However, the conceptacles occasionally are 

 almost immersed and the roof is not dissolved. In such cases the 

 conceptacles consequently become overgrown. The sporangia are 

 four-parted, about 60—80 p long and 20 — 35 p broad. In f. squa- 

 mulosa the conceptacles resemble those of the typical form, though 

 they are frequently less crowded. This form is often sterile. In 

 f. subloevis the said conceptacles are generally more depressed and 

 a little larger than in the forms mentioned, 300 — 400 \j- in diameter. 

 The conceptacles of cystocarps in this species often appear in the 

 same individual as those of sporangia, but either frequently in 

 greater number They are hemispheric-conical or subconical and 

 of about the same size as those of sporangia. The conceptacles 

 of antheridia are of the same shape as those of cystocarps, but 

 only 150—200 />. in diameter. 1 ) 



This characteristic and well known species is found attached 

 to rocks and stones, or to shells of mollusks, exceptionally to other 

 calcareous algae. It occurs in the lowest part of the litoral region, 

 where for the most part it is partly sheltered by other algas, e. g. 

 Fucus, and besides it is found in large numbers in the sublitoral 

 region. The alga here descends to the depth of 8, or, towards 

 its southern limit of distribution, sometimes even 16 fathoms. It 

 shows, on the whole, a remarkable power of accommodating itself 

 to the circumstances. Thus it occurs both on the open shore, 

 often even in localities much exposed, and in sheltered places in 

 the fjords. At the isle of Bornholm in the Baltic, where the sea 

 is but slightly saliferous, Dr. Rosenvinge has found it in rather 

 considerable number in a single place at the lowest water-mark. 

 The specimens were almost typically developed, but somewhat 

 encumbered by other algas, and they were sterile, when being 

 collected in the former half of July. In the Mediterranean and in 

 the Adriatic it now and then occurs in grottoes above the highest 

 water-mark. But it is here never well developed and seldom bears 



i) Here and in the sequel unless it is otherwise observed, the shape and the 

 size of the conceptacles are concerned, as seen from the surface of the 

 plant. 



