33 



with conceptacles of sporangia. The named form is characterized 

 by its in general apparently more vigorous and coarse branches, 

 which probably as a rule become much anastomosing and in part 

 even nearly to the apex, the latter being thick and rounded. 



The structure of the frond agrees in the main with that of L. 

 fruticulosum. The cup-shaped layers of tissue are rather regular. 

 The inner cells of these layers are about 12 — 16 fi long and 6 — 8 

 /a thick, thus in general apparently a little larger, and often a little 

 thicker in proportion to the length than in the named species. 

 Overgrown conceptacles are partly scarce partly numerous. 



The cystocarpic conceptacles, which are mentioned by Hauck 

 1. c, are conical, low, and about 400 p. in diameter at the base. 

 They are at the summit intersected with a canal, which, contrary 

 to most other species, appear to be formed in a rather advanced 

 state of the development of the conceptacles, as in others and 

 apparently nearly fully developed ones the canal was not visible. 

 I, however, have seen but some few ones in one of Hauck's 

 specimens of the typical form. The carpospores are much varying 

 both in shape and size. 



I found conceptacles of sporangia in the above mentioned 

 specimen of the form capitellata from Hauck's herbarium. They 

 are scattered or somewhat crowded towards the apex of the 

 branches, slightly prominent and in general rather flattened, 350 — 

 450 fi in diameter, seldom less. A British specimen mentioned 

 below has been richly provided with conceptacles of sporangia, 

 scattered and in part crowded nearly over the whole frond, but it 

 is dead and the roofs quite dissolved except some few according 

 to those quoted. However, judging also from the holes after the 

 conceptacles, they seem to have been a little smaller, or about 

 350 — 400 /-/■ in diameter. In the above named Norwegian specimen 

 I also found some similar conceptacles. The canals appear not to 

 be numerous. I have numbered about 30 — 40. The sporangia, 

 of which I have seen but some few, are four-parted and about 

 160 fi long and 40 ;j. broad. 



Remark on the synonomy. It is a fact, that in Lithotham- 

 nion the various species have been more confounded and diffe- 



