4 ART. 14.-K. YEN DO: 



». 



EXTERNAL APPEARANCE OF GENICULA. 



The genicula of Corallinœ appear with a brownish colour while 

 the plant is yet living. In some of the members which have no 

 significant genicula, the colour is, as a consequence, not remarkable. 

 When the fronds are bleached and the articuli have turned into 

 chalky white, the genicula are distinguishable as yellowish brown 

 constrictions or rings around the calcareous fronds. 



The genicula are entirely free from the deposit of calcium, and 

 the substance is horny and flexible. This gives a special character to 

 the fronds. Whether a frond is rebust or not depends essentially 

 upon the relative size of the genicula and the accompanying articuli. 

 Even in an individual the proportion differs in the basal and the 

 upper parts of the frond. 



The majority of Corallinœ have very short genicula at the basal 

 part of the frond. The articuli at this region are mostly short and 

 cylindrical. Hence the stem at this part becomes moniliform, the 

 genicula taking the places of the constrictions. Amphiroa dilatata, 

 Amp. Bowerbanhii, Amp. canaliculata, Amp. ephedrcca, etc., in short, 

 those which would be grouped under the section Eun/tion, Dene., 

 have the genicula with equal or nearly equal, diameter with the 

 articuli adjacent. 



The genicula of Amp. stelligera, Amp. Charoides and their allied 

 forms are the larger than those of the other species. Some of the 

 matured genicula, indeed, are longer than the accompanying articuli. 

 They are cylindrical, smaller in diameter than the articuli. 



When the fronds of the Corallinœ are observed with the naked 

 eye, we can easily distinguish several forms of the genicula. These 

 multitudinous shapes might be classified briefly into the following 

 five types : 



