r. CERAMIACE^. 221 



confounded by the elder Agardli with P. asplenioides, from which this species is 

 abundantly distinct. 



Plate XXXII. A. Fig. 1. Ptilota lu/pnoides ; the natural size. Fig. 2, portion 

 of a larger and lesser branch, with fertile ramuli ; Jig. 3, a fertile ramulus, with 

 oblong clusters of tetraspores ; fig. 4, tetraspores ; fig. 5, transverse section of the 

 base of the stem ; the latter figures more or less highly magnified. 



3. Ptilota asplenioides., Ag. ; frond piano-compressed, two-edged, decompound- 

 pinnate ; pinufe opposite, unlike ; one undivided, serrulated, the other (abortive or) 

 pinnately parted ; pinnula^ erecto-patent, decurrent, scymitar-shaped, incurved, 

 acute, serrulate, areolate ; fruits marginal, supra-axillary, the tetraspores in dense, 

 roundish, pedicellate glomeruli ; the favelloa involucrate, the branches of the invo- 

 lucre pinnellated with articulate, single-tubed ramelli. /. Ag. Sp. Alg. 2, p. 98. 

 Ehodocallis asplenioides, Kiitz. Sp. Alg. p. 674. Fucus asplenioides, Turner, Hist. Fuc. 

 t. 62. Esper. Ic. t. 147. 



Hab. Northern Pacific Ocean. Prince "William Sound, Russian America, Mr. 

 Menzies. (v. s. in Herb. T. C. D.) 



Frond twelve to eighteen inches long, a line or more in breadth, with a strongly 

 compressed stem, which is slightly winged above, two-edged below, veiy firm, 

 opaque and cartilaginous in its lower part, gradually flatter and thinner toward the 

 summit, single or divided into several principal branches or secondary fronds. The 

 mode of branching is pinnate ; the pinnation repeated many times in large specimens 

 after a uniform system, which is easily understood by examining one of the lesser 

 branches of an old plant, or the apex of the main stem in a younger plant. Such 

 branch has a piano-con i pressed rachis, distichously pinnate with normally opposite, 

 but very different looking pinna3. One pinna of each pair is undivided, about two 

 lines long and half a line wide, cultriform, acute, erecto-patent and somewhat 

 incurved, more or less distinctly serrated or serrulated, rarely nearly entire, its 

 lamina vertical (in the same plane as the flat rachis) the lower edge decurrent or 

 gradually fining off" into the rachis. The opposing pinna when developed, for it is 

 frequently abortive, is many times longer and is again pinnated on a similar plan. 

 In the subsequent divisions of the frond the undivided-cultriform pinnaj and pin- 

 nules are often alone perfected, and these constantly alternate with each other ; the 

 place of the pinnately-parted pinna? being merely indicated by a minute ramulus 

 or even reduced to a rapidly obliterated process. In such specimens the frond 

 seems alternately pinnatifid, as figured and described by Turner, but the examina- 

 tion of a young branch shows that this is a deceptive appearance. The pinnaj and 

 pinnula? are coated with a uniform surflxce of small polygonal cells. AVhen held 

 between the eye and the light, and examined with a jocket lens, a slender medial 

 line (the axial filament) is seen running through the frond, and sending ofl 

 branches to each pinnule ; this line of cells, in the pinnule, running nearer to the 

 upper than to the inferior margin. The serratures of the margin arc very variable 



