275 



This species is usually classed under the genus Jania, established by Lamouroux. 

 This genus, however, is, as shown by Areschoug (1. 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. 198A). 

 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 coincide, 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- 

 mification may also occur. A greater or 

 smaller number of the joints may be com- 

 planated, obsagittate and bearing on the up- 

 wardly directed points two opposed simple articulated pinnulae consisting of a small 

 number of joints. When these pinnulae 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 pinnulse, under the forking 

 branches. The pinnulse, 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 pinnulae or pinnae may sometimes arise at the growing point, 

 for according to Kny (1. 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 adventitious pinnulse may 



35* 



Fig. 198. 



Corallina rubens. A, basal part of an articulated frond 

 springing off from the basal disc. B, adhesive disc 

 developed at the end of a branch. 65:1. 



