34 



specimens of both forms. 1 li< ■ form haingsisiana is partly attached to other hard objects, as 

 the specimens of f. americana hitherto known, and then gradually forms a thin crust over the 

 substratum, partly it develops itself freely, or detached parts of the plant continue their growth 

 freely, on the bottom. In the latter cases it may - in a young stage - show an appearance 

 somewhal diverging from older and densely branched specimens (PI. III, fig. i — n). This 

 form is - for the rest somewhat varying both in habit and in structure. Among the rather 



great numb cimens from stat. 303 there are some less typical ones, showing a more 



irregular branching, and less fastigiate (PI. III, fig. 12 and 151. Others an- a little coarser 

 and show transition to i. subjlabellala. As stated 1. e., the branches of I. americana are mostly 

 1.25—1.75 mm. thick. The branches of f. haingsisiana are generally of the same thickness. 

 But particularly in specimens that are more or less aj ; 1 >ach:.":g to f. subfiabellata, the branches 

 may be about 2 mm. thick. The majority of specimens from stat. 240 are also less typical, 

 partly in habit, partly also in structure, particulars of which are found below. They are also 

 somewhat stunted and much burdened with extraneous objects. (PI. III, fig-. 21 — 22). The 

 mens in hand trom stat. 193 partly resemble typical f. haingsisiana, partly they are a 

 little coarser. A single specimen from each of the stations 93 and 149 is in habit most closel] 

 allied to the same from stat. 240. In f. americana as well as in f. haingsisiana the upper part 

 of the plant may be somewhat worn by the action of a very strong current. In such specimens 

 the branches are more or less truncate. Live specimens of f. haingsisiana are pink-coloured, 

 judging from a coloured specimen in the collection. In dried state it is mostly whitish or slightly 

 purplish, frequently, however, with a greenish shade. It attains a diameter of about 9 cm. 



The form subfiabellata is distinguished by its compressecl and less crowcled branches or 

 more or less flabellate branch-systems. It is a little coarser than f. haingsisiana. the branches 

 usually being 2 — 2,25 mm. thick (PI. III, fig. 23 — 25). Of the specimens here picturecl fig. 23 



represents an intermediate form between the forms mentioned. 

 Both seem to have occurred associated with each other. The 

 form subfiabellata is coarser and also in other respects some- 

 what diverging from the form prostrata known from Bermuda. 

 As regards structure, I have mentioned before (1. c.) 

 that the cells of f. haingsisiana are often slightly broader, with 

 slightly thicker walls, than those of the type of the species. 

 From an examination of a number of specimens off. haingsi- 

 siana. the structure proves to be so far varying that in this 

 respect too no line is to be drawn. In f. americana the cells of 

 the medullary hypothallium are in general about twice as long 

 as broad, partly however longer, partly and often shorter, or 

 12 — 22, here and there but 10, frequently 14 — 1S <j_. long and 

 7 — 10, seldom up to 12 u.. broad, with rather thin walls. The 

 perithallic cells are partly square, 4 — 6 u.. in diameter, partly 

 and most frequently vertically elongated and 7 — 12 or seldom 

 up to ! mg (Fig. 16). In f. haingsisiana the medullary hypothallic cells resemble those 



Vvv\t t i Vu 



i ;\ branch: X 72. 



