A REVISED LIST OF CORALLINE. 15 



DERSON^^ witbout any comment, but probably strengthened by 

 Prof. Farlow's remark on this species.^^* 



It has, however, unique characters not mentioned by its dis- 

 coverer or others, as far as my research has extended. The 

 peculiarty lies in the genicular structure and in the branching 

 mode of the fronds. It has no geuiculum, in the exact sense, 

 similar to any of the other Corallince. The geniculum is formed 

 by the lower half portions of the filamentous periclinal cells, 

 the upper half of which practically corresponding to the medulla 

 of other species. The details are given in my former paper. ^^ 

 The axial stems ramify dichotomously while the ramuli start from 

 the margins of the articuli of the stem. An articulus which sends 

 forth dichotomous branches from its top has a longitudinal furrow 

 along its median. Hence the articulus apparently seems to be 

 two compressed articuli fused together by their periclinal sides 

 with a geniculum on the top of each. The furrow or the canaliza- 

 tion is also visible in the succeeding lower articuli, gently dis- 

 appearing as we trace downwards. The two genicula on the top 

 of the branchino; articulus are not in a strai2;ht line but form 

 a geometrical supplimentary angle to the axile divergence of the 

 branches. The angulation of the genicula is also distinct in the 

 succeeding articuli, but gradually approaches a straight line as 

 canalization vanishes. 



The canalization and the mode of pinnation of ramuli are 

 unique characters among Corallince. The solitary conceptacles on 



1) Zoe. Vol. II. p. 225. 



2) Proc. of Amer. Acad. Vol. XII. p. 239. 



* These two papers were not accessible to me. But findin;j; them indispensable in 

 preparing the present chapter, I asked Mr. F. S. Collins for references. Mr. Colliks 

 was so kind as to send me a transcript of all the lines relating to the subject. I desire to 

 express to him my heartiest thanks. 



3) Study of Genicula. p. 16. 



