This species is usually classed under the genus Jania, established by Lamouroux. 
This genus, however, is, as shown by ARESCHOUG (I. c. p. 554), scarcely different from 
Corallina by other characters than the normally forked frond. Mrs. WEBER has 
later (Siboga, p. 85) stated that there is also an anatomical difference, the cells of 
the central tissue in the joints being of almost the same length as those of the 
genicula, while they are much shorter in the true Corallina. I prefer, however, to 
regard Jania as a subgenus of Corallina. 
The articulated fronds are given off from a small thick crust with lobed out- 
line, resembling that of C. officinalis but of smaller size. From the crusts examined 
by me only a small number of fronds, 
usually 1—3, were given off. The fronds 
are connected with the crust by a geniculum 
which may be rather broad (high) (fig. 198 À). 
The fronds are normally forked, the point 
of vegetation producing by the ramification 
no shoot in continuation of the axis, but 
two diverging equally from its direction. 
The bifurcations occur in greatly varying 
frequency, the number of interjacent joints 
varying from 1 to 10 or more. The planes 
of ramification of the successive bifurcations 
do not coïncide, but cross each other under | 
various angles (comp. Kny, 1872 p. 707). In ( 
most of the Danish specimens this is the \_ 
only ramification existing; but pinnate ra- er 
. 9 Fig. 198. 
mification may also occur. A greater or Corallina rubens. A, basal part of an articulated frond 
smaller number of the joints may be com- Springing off from the basal disc. B, adhesive disc 
0 o developed at the end of a branch. 65:1. 
planated, obsagittate and bearing on the up- 
wardly directed points two opposed simple articulated pinnulæ consisting of a small 
number of joints. When these pinnulæ are produced in a greater number, on 
several successive joints, we have the f. corniculata, which has been regarded 
as a distinct species, but which cannot be kept distinct from the typical species. 
The joints at the base of the bifurcations may also bear pinnulæ, under the forking 
branches. The pinnulæ, no doubt, usually arise later than the branches of the 
bifurcations, and may then perhaps be regarded as adventitious organs; but it seems 
that opposite lateral pinnulæ or pinnæ may sometimes arise at the growing point, 
for according to Kny (l. c. sp. 707) “trichotomies” may also occur. This must take 
place when the ramification is pinnate. In such cases the middlemost shoot cer- 
tainly represents the continuation of the axis, and the two lateral ones correspond 
to the branches of an ordinary bifurcation; I have not, however, examined such 
ramifications. In rare cases the lateral shoots showed a more vigorous development, 
and were bifurcate as the ordinary shoots. Supernumerary adventilious pinnulæ may 
35* 
