116 M. FOSLIE. [1905 



bling the species in question both in structure and in the said 

 young conceptacles as well as in a number of grown-in ones, and 

 likely being identic. 



As to structure, the hypothallic cells in this species are partly 

 short, partly elongated, 14 — 40, sometimes 50 p lung, by 9 — 14 p. 

 The perithallic cells are rather varying, now 10 — 20 p long and 

 8 — 14 }i broad, now up to about 30 p long. It is, however, to 

 be observed that only a couple of sections have been examined. 



The conceptacles of sporangia are immersed, not, or scarcely, 

 raised above the surface of the frond, 90 — 130 p in diameter, finally 

 sligthly decorticated as in L. orbiculatum, with, a single pore. In 

 a median vertical section they are about 150 p in diameter, judging 

 from a few measures. The sporangia are four-parted, 70 — 100 ji 

 long and 30 — 40 p broad. The said conceptacles are gradually 

 overgrown and are then to be seen in rows parallel to the surface 

 of the frond. 



As to the questionable synonymy recorded above, viz. Melobesia 

 sp. admitted with doubt by Prof. Kj eilman l..c. under M. Lejolisii, 

 I have seen an authentic specimen from Spitzbergen. It forms a 

 small crust composed of several layers of cells, and seems to me 

 to belong either to the species in question or to be a form of 

 Ph. compactum 



This species is on one hand nearly related to LithopJi. orbi- 

 culatum, and on the other hand it approaches Lithoph. macrocarpum 

 f. Laminarice. Sterile specimens will be confounded with the latter, 

 though they are less extented, usually thicker, less brittle and less 

 decreasing in thickness towards to edge. Besides, the colour is 

 in fresh specimens a rather pale purplish one, always paler than 

 in L. macrocarpum f. Laminarice, and the latter becomes usually 

 a little darkish in drying, whereas on the contrary L. Crouani 

 usually becomes lighter. In habit it also often recalls Ph. compaction, 

 even if bearing young conceptacles. 



The alga occurs mostly in a depth of 2 — 8 fathoms both on 

 the open coast and in places rather sheltered in the fjords. It 

 is scantily furnished with sporangia in the months of March and 

 June — Juty. 



