362 Johnson. — On Stenogramme interrupt a, 
(Fig. 1 s). Each sorus consists of innumerable vertical rows 
of cells, the individual cells in each row being the mother- 
cells of the tetraspores, each ultimately dividing into four 
tetraspores, cruciately arranged. As the sori arise from the 
superficial cells of the thallus by repeated horizontal divisions, 
it is not difficult to see how, by examination of young sori in 
certain stages (Fig. 3 s)> one may be led to consider such a sorus 
as a mature one showing zonate tetraspores, a mistake which 
has been more than once made in the case of .S'. interrupt a x . 
Male Plant. 
In a male specimen of Stenogramme inter rupta the anthe- 
ridia are recognisable, in a fresh plant, as pale patches occur- 
ring in the upper part of the thallus on opposite sides of 
it (Fig. 4). Each antheridium is nearly as broad as the 
thallus-segment on which it occurs, may be as long as or 
longer than it is broad, forms a slight elevation on the surface 
of the thallus and is homogeneous, i. e. consists of closely 
applied spermatium-mother-celis, without intervening sterile 
thallus-cells (Fig. 5)* Towards the edges of the antheridium 
there is, as is to be expected, a tendency to the interruption 
of the homogeneity. I saw nothing to suggest that the sper- 
matia are not quite normal (Fig. 6). 
Female Plant . 
S. interrupta is readily distinguished from all other Florideae 
by the midrib-like, or nerve-like, more or less continuous simple 
or forked line found running along the centre of the segments — 
more especially the upper ones — of the thallus of the female 
1 In Grevillea III (1874), E. M. Holmes described and figured, as he then 
thought for the first time, tetrasporic plants of S. interrupta. In Grevillea IV 
(1875), E. P. Wright showed that Harvey had described and figured such plants in 
his Phycolog. Austral. (IV. PI. CCXX, Figs. 2-5), and that he had in his Nereis 
Bor. Amer. (Part II. p. 162) acknowledged the priority of the late Miss Gifford as 
the discoverer of the tetrasporic plants. I refer to this matter, to prevent others 
from falling into the same mistake as I nearly did through finding in De Toni’s 
Sylloge Algarum a reference to Holmes’ paper but not to Wright’s correction, and 
also to state that I find (Fig. 3) the sori on both surfaces of the thallus as Montagne 
did, and as Holmes states he was, himself, unable to do. 
