321 
tetrasporangia should in C. spiniferum be greater than in the last named species; in the 
Danish specimens, these organs reach the dimensions stated for C. spiniferum, the goni- 
Fig. 233. 
Callithamnion tetragonum var. fruticulosa. From Hellebæk. 
Upper part of sterile branch. The first branch of the 
second order is marked with X. 200 : 1. 
moblasts being 130—227 «u in diameter, 
and the sporangia being 74—81 w long, 
46—61 w broad. 
As stated by Kyvin, L. c., all the forms 
referred here to C. tetragonum agree with 
each other in branching and all mor- 
phological characters. Referring to Ky- 
LIN’s descriptions, I shall here describe 
the specimens occurring at the North 
coast of Sealand, all referable, in my 
opinion, to the variety that J. AGARDH 
designated by the name of fruticulosum. 
= 
Callithamnion tetragonum var. fruticulosa. Part of 
stem showing cortication and adventitious branches. 
50 : 1. 
The plants reach a length of up to 7 cm; in aspect they resemble the typical 
C. tetragonum and have the same brownish red colour. The main branches have a 
pyramidal outline. The main axes are vigorous, straight and covered with a cortex 
of decurrent filaments, from which here and there adventitious shoots are given off 
Without any distinct order; young and older shoots may arise intermingled with each 
