woo.] PRINCIPLE OF SYSTEMATIZING CQRALLLINJE. 125 



four genera — Arthrocardia, Cheilosporum, Corallina and Jania. This had 

 never been so definitely done by the other writers. In Litharthron, 

 Metagoniolithon and Lithothrix, the articuli and genieula have the peculiar 

 structure characteristic of each genus. In the minor points of the cellular 

 arrangement, Jania and Cheilosporum have some characters differing from 

 Corallina and Amphiroa. Kiitzing's remark that every genus of the 

 Coralline may be distinguished by its proper structure, is now partly verified 

 but probably more sharply than he had expected. 



4. Genieula. The genieula, whose presence or absence in the Coral- 

 linacere is the essential point in dividing the family into two subfamilies, 

 have not been thought very weightly in consideration of the generic dis- 

 position. But after studying the genieula in the representatives of every 

 genus and section, I found that those which have characters in common 

 in the articuli and conceptacles, more or less concide in the characters 

 of genieula. As has been already remarked in my former paper the mul- 

 tizonal genieula are limited to Amphiroa (Eurytion) and to Metagonilithon 

 stelligerum and its allies. The former has several other common external 

 characters ; and the latter is characterized by the verticillate ramuli which 

 have no parallelism in the other genera. And Lithothrix aspergillum, the 

 peculiarity of the outward appearance of which impeled J. Gray to establish 

 a new genus, has aberrant structure of the genicula. 2) 



It would not be advisable to put too much stress on the genicular charac- 

 ters. The geniculation is a physiological necessity of the plant and may not 

 be any valuable character in the phylogenetic conception. But it must be 

 admitted to say that it is probably the steadiest character next to the mode of 

 the fertilization in the Corallina?. The relative position of genieula in a 

 frond may vary according to the condition of the environment or by the 

 influence of the external factors, but may never undergo any fundamental 

 change in its mode of formation. The difference of the structure of genieula 

 so far as it is related to their mode of formation should be an important 

 matter to discuss. It may not divide the genera or subgenera on that 

 account only, but can with utmost certainly define a group in connection 

 with other common characters. This has been mentioned in my paper. 



Taking the above considerations into accounts I have arranged the all 

 species of Corallina? hitherto appeared in literatures. The paper will be 



1) Study of Genieula. p. 30-32, 



2) 1. c. p. 16. 



3) I.e. p. 41. 



