V. GELIDIACE.E. 121 



cross section through one of them shows that they are deeply sunk in the substance 

 of the branch, being wholly formed out of a portion of the axial filaments. The 

 walls are constructed of filaments, derived from the axis, and very densely inter- 

 woven together, and invest the sporiferous nucleus on all sides, enclosing it as 

 within a sac. Numerous slender filaments proceed from the inner face of the walls 

 to a central placenta, formed likewise of a dense plexus of filaments. The Avhole 

 exterior surface of the placenta is densely clothed with pedicellate, oblong or pear- 

 shaped spores, which are either simple, or (perhaps with age) divided transversely 

 into two or more, chained sporules. The tetraspores are of small size, and scattered 

 without order through the surface cells of the branches and ramuli. 



In external habit and even in the internal structure of the frond there is a very 

 close similarity between the species of this genus and of Rliahdonia^ so much so, 

 indeed, that it is impossible to tell, without examining the conceptacular fruit, to 

 whicli of these genera any individual specimen may belong. The sporiferous 

 nucleus is however very different, but I know of no other characters by which to 

 distinguish Ehabdonia; and before I became aware that the American specimens now 

 to be described were identical with the European Solieria chordalis, I had referred 

 them without hesitation to lihahdonia. The genus Solieria was founded by Prof. J. 

 Agardh on an Alga first found at Cadiz, and which had been referred by the elder 

 Agardh originally to Sphcerococcus ; then to Deksseria ; and which was afterwards 

 associated with Gracilaria by Dr. Greville, and with Gigartina by Dr. Montague, 

 from all which genera, as now reformed, it is needless to say that it is abundantly 

 different. In external habit it most resembles Gracilaria (Plocaria), and may even 

 be confounded Avith G. compressa ; and before structure of frond and of nucleus 

 were minutely examined it might very well have found a place in the group so 

 called. Though originally observed in Europe, it seems to be much more abundant 

 along the American shore, where its range extends from Long Island to Florida. 



]. Solieria e/wrfZa&, J. Ag. ; frond alternately decompound; lateral branches 

 long, virgate, tapering to the base and apex, and furnished with more or less copious 

 linear-fusiform, acuminate ramuli ; conceptacles copious, half immersed in the 

 branches. /. Ag. Alg. Medit. p. 157. /. Ag. Sp. Alg. 2, p. 723. Kiitz. Sp. Alg. p. 

 748. Deksseria chordalis, Ag. Sp. Alg. 1, p. 189. Gigartina Gaditana, Mont, in 

 Webb. Ot. Hisp. t. 7. (Tab. XXIII. A.) 



Hab. Abundant in Long Island Sound, from Cape Cod to New York, Prof. 

 Bailey, &c. Longbranch, New Jersey, Miss Morris. Charleston Harbour, H. W. 

 Ravenel, Esq. and W. H. H. Apalachicola, T. Drummond, Dr. Chapman. Key 

 West, W. II. H. (v. V.) 



Frond from six to twelve or fourteen inches long, from half a line to nearly two 

 lines in diameter, much ])ranched but very variable in the ramification. Commonly 

 a subsimple stem is set throughout at short distances with many lateral branches, of 

 which the lowest are longest, the i-est successively shorter upwards. These branches 



VOL. IV. AKT 5. ^* 



