ANTENNULARIA RAMOSA. 283 



of A. ramosa, unwittingly increased the confusion by 

 basing his diagnosis mainly on a character which has no 

 real existence ! 



The distinctive points, however, are sufficiently marked 

 and are to be found not only in the ramification and 

 general habit, but also in the minute structure. 



Mr. Alder was the first to indicate, and with his usual 

 accuracy, the differences in detail between the two species; 

 but even he has omitted one or two characters of consi- 

 derable importance. In general aspect A. ramosa and A. 

 antennina are strikingly dissimilar, the luxuriantly branched 

 and tree-like shoots of the former offering a decided contrast 

 to the long, simple, and thread-like stems of the latter. 

 But the difference is not due only to the ramification. 

 The stems of A. ramosa are much thicker than those of its 

 ally, and the whorls much more closely set upon them; 

 they are therefore more densely clothed with the branch- 

 lets ; and as these are longer than in A. antennina, and 

 more numerous in each verticil, they give a peculiarly 

 stout and rotund appearance to the shoots. 



The ramuli are long and somewhat recurved, and have 

 none of the sickle-like shape which is characteristic of 

 those of the preceding species ; they are made up of 

 straight internodes of about equal length, each of which 

 bears a calycle. The short intervening internodes, sup- 

 porting a nematophore only, which occur in A. antennina, 

 are wanting; in A. ramosa the corresponding nemato- 

 phore occurs on the internode that bears the hydrotheca. 



Had. Generally distributed ; as abundant as the prece- 

 ding. At Peterhead and Wick, Mr. Peach informs me, it 

 is commoner than A. antennina ; and so it is, according to 

 Macgillivray, at Aberdeen. It is very fine and abundant 

 in Shetland. 



[South Africa (Busk).] 



