than ordinary depth differ as much from their normal state, and 

 in a very similiar manner, as the present does from S.filici?ia. 

 Persons accustomed to dredging must be familiar with states of 

 Plocamium coccineum, Dasya coccinea, &c, which are more slender 

 than the normal form, irregularly branched, with very patent 

 branches and ramuli, and which are usually found entangled 

 with other Algse, to which they are attached by hooked processes, 

 different from their true roots. The plant here figured has always 

 appeared to me to be a simliar state of S. Jilicina, nor am I yet 

 convinced that it ought to be regarded as any thing more. Other 

 observers are, however, of a different opinion, and among them 

 Mrs. Griffiths, who has repeatedly gathered both plants, and con- 

 siders the constantly parasitic habit of the S. Sertularia, its small 

 size, and very patent branching, to afford sufficient distinctions. 

 In the plate here given I have taken pains to represent all these 

 characters in sufficient detail to be readily contrasted with S. Jili- 

 cina figured in the last plate, and having done so I must submit 

 the decision to the judgment of my fellow students. At any rate 

 there are quite differences enough to constitute an excellent 

 " cabinet species". 



1 am not aware in what work Bonnemaison has published this 

 plant. My knowledge of his synonyme is due to M. Lenormand 

 who has obligingly communicated a specimen from the north of 

 France under the name here adopted, and who informs me that 

 it is frequently cast on the French coast entangled with the un- 

 cinate variety of Plocamium coccineum. 



Fig. 1. Sphacelarja Sertularia ; of the natural size. 2. A branch. 3. A 

 pinna. 4. Apex of a pinna, with some of the smaller pinnules. 



