50 



development. It frequently appears to form widely extended and 

 more or less dense banks. 



Occurrence. Hero in Helgeland, rather local but abundant 

 (Kr. Schreiner); Hestvser atFrooerne in Sondre Trondhjem's Amt, 

 local but abundant; the Skjorn Fjord (a branch of the Trondhjem 

 Fjord), rather local but abundant, forming great banks especially 

 at ,,Dalsoren". 



Lithothamnion delapsum Fosl. mscr. 



L. fronde initio circum lapides vel conchas effusa, demum 

 libera, fornicata, parte centrali solida vel lobata, vel demum crustam 

 tenuissimam formante, ramis brevissimis, subdichotome ramosis, 

 plerumque valde coalitis, 1 — 1.5 mm. crassis instructa, apicibus 

 obtusis; conceptaculis sporangiferis convexiusculis vel seepe plano- 

 convexis, parum prominentibus, a superficie visis diametro 350 — 

 400 (i; sporangiis (binas sporas foventibus?) 120 — 160 [>■ longis,, 

 40—60 p. latis. 



f. abbreviata Fosl. mscr. 



f. ramis confertis, fastigiatis. Tab. 14, fig. 1 — 3. 



f. conglutinata Fosl. mscr. 



f. ramis fasciculos breves, minores formantibus. Tab. 14, fig. 4. 



Syn. Lithothamnion fornicatum var. Fosl. Contrib. 2. p. 5, t. 1. 



Remark on the species. In Contrib. 1. c. I mentioned under 

 L. fornicatum a couple of forms partly reminding one of and 

 growing together with the named species partly approaching Z- 

 JJngeri (L. fruticulosum in the present paper), and one of these 

 were figured 1. c. The organs of propagation then were unknown 

 in both. By closer examination of these specimens I found con- 

 ceptacles of sporangia, and I also found the latter growing down 

 into the frond. These forms I here record as a distinct species, 

 but I am not sure whether they ought not, perhaps, to be consi- 

 dered as two separate species, as they somewhat differ in their 

 development. However, judging from the scanty materials at my 

 disposal they seem to belong to one and the same species. 



Description of the form of the species. The form abbreviata 



