No. 3] REMARKS ON NORTHERN LITHOTHAMNIA. 71 



On the coast of Scotland the two forms last mentioned seem oc- 

 casionally to grow gregariously. 



The species occurs in a depth of 3 — 18 fathoms. In the 

 Gulf of Naples it is said to have been picked up from a depth of 

 30 fathoms. It prefers places sheltered, but also appears in ex- 

 posed ones. Cp. Lithoth. Adriat. Meer. etc. p. 9, and A Visit to 

 Roundstone (The Irish Naturalist, Vol. VIII, 1899), p. 176. It has 

 been found with conceptacles of sporangia in small numbers in 

 the months of April — August, but without sporangia. 



As to the occurrence and the geographical distribution of the 

 species, the form met with on the south west and south coast of 

 Norway represents a delicate form of f. squarrulosa with transi- 

 tions to f. palmatifida. It is, however, very scarce. Besides, dead 

 specimens of a coarse f. squarrulosa have been found in two 

 places (Rovaer and Mandal). Similar forms of the species have 

 been found on the coasts of Denmark, here, however, also transi- 

 tions to f. coralloides and f. compressa as well as f. subsimplex. 

 Here the alga seems to occur in larger number than on the coast 

 of Norway. On the coasts of the British Isles the species is 

 common and in many places abundant, and all the forms have 

 been found there. So also on the Atlantic coast of France, where 

 particularly f. coralloides and f. compressa seem to be common in 

 many places, but also f. squarrulosa occurs rather numerously. 

 Besides, all the forms seem to occur in part rather abundantly in 

 certain places in the Mediterranean. But only a delicate form of 

 f. squarrulosa occurs in the Adriatic, and apparently very scarcely. 

 Cp. Lithoth. Adriat. Meer. 1. c. 



Area: Norway: Espevaer (Gran!), Haugesund (Witt rock, 

 Areschoug, No rum I) 1 ), Rovaer, dead specimens (No rum!), 

 Mandal, dead specimens (Wille!,!); Denmark (Rosen vinge!), 



J ) L. calcareum is, in fact, included in L. norvegicum Aresch. Obs. Phyc. 3, 

 p. 4. Among a number of authentic specimens of the latter I found a few 

 ones belonging to the former species. It seems to occur very scarcely in 

 the periphery or in the neighbourhood of the bank where L. norvegicum 

 was first collected by Professor W i 1 1 r o c k, described by Professor 

 Areschoug, viz. Vipransund near Haugesund. 



