A STUDY OF THK cKXh'l'LA OF CORALLINK. H 



The extreme case of pinnatioo is that of Amp. aspergillum. The 

 more or less coin pressed articuli of the main stem are regularly jointed 

 at certain distances. The genicula are linear, with subequal diameter 

 to the articuli. The primary articulus of the branchlets arise decussate- 

 ly from the upper end of the periclinal edge of the compressed 

 articulus. The insertion of the pinnae or the primary genicula is 

 at right angles to the axial geniculum. 



As the position of genicula is dependent upon the mode of 

 branching, the plants with irregular branching have naturally the 

 genicula at indefinite positions. The larger number of the section 

 Euamphiroa, Dene, are examples of this category. 



In Amp. valonioides a branch often arises obliquely upwards from 

 the distal end of an axial articulus with its primary geniculum at 

 some distance further than the diverging point. This gives an 

 appearance of sympodium until we examine the internal structure, 

 cf. Cor. verœ Japon. PI. I. fig. 3. 



Amp. cretacea has an irregular mode of branching. It sometimes 

 gives out branches at the distal end of an articulus showing apparant 

 dichotomy. On the other side, several branches arise decussately 

 from the periclinal side of a cylindrical articulus. The latter is by 

 no means the abnormal but a special mode of ramification belonging 

 to this species, cf. PI. IV. fig. 2. 1. c. 



These decussate branches have the primary geniculum in two 

 forms. The first is that of the geniculum directly situated upon the 

 surface of the axial articulus ; that is, the geniculum starting without 

 any process on the surface of the articulus. The second form has the 

 genicula upon the process, perpendicular or obliquely, produced on 

 the surface. These modes of geniculation might correspond to 

 " direct " and " indirect " dichotomv. But the character is not 



