MARINE ALG.E OF BEAUFORT, N. C. 457 



throughout the zones on the older portions of the thallus; antheridia and oogonia borne on separate 

 plants (dioecious), occurring in sori in concentric bands, as with the tetrasporangia, borne on both sur- 

 faces, usually predominantly on the lower surface, oogonia covered by a thin, subpersistent indusium, 

 antheridia naked (not covered by indusium); texture membranaceous; color ^ight brown, sometimes 

 olivaceous. . 



Thallo erecto, piano, expanso, 4-22 cm. longo, 5-37 cm. lato, juvenescente integro, maturascente 

 interum atque interum plus minus alte ex marginibus laciniato, segmentacuneato-spatulataautflabellata 

 formante, aliquando calce incrustato, zonato ab lineis piliferis cum marginibus parallelis, in regionibus 

 vetustioribus saepe obscurescentibus, zonis interpilis 1.5-6 mm. latis, basi stipe densa rotundata 3-12 

 mm. longa, rhizoideis fulvis dense tecta, disco basali apta; lamina prope revolutas apicales margines 

 ex tribus stratis cellularum, per maiorem partem thalli ex quattuor stratis cellularum, ad basim ex sex 

 aut octo stratis cellularum constante, cellulse epidermis circiter dimidio breviores quam cellulae centrales; 

 tetrasporangiis ab indusio tenue et subpersistente tectis, in utraque superficie, plerumque pro maiore 

 parte in inferiore superficie, in lineis unis aut duobus cum margine apicale parallelis circiter in una- 

 quaque media zona interpilula productis, his lineis hinc inde fractis, tetrasporangiis in partibus adul- 

 tioribus thalli per zonas sparsis; antheridiis et oogoniis ab plantis diversis in lineis concentricis sororum 

 similiter tetrasporangiis, in utraque superficie, plerumque pro maiore parte in inferiore superficie pro- 

 ductis; oogoniis ab indusio tenue et subpersistente tectis, antheridiis nudis (et non ab indusio tectis); 

 substantia membranacea; colore dilute fulva, aliquande olivacea. 



North Carolina to Florida; West Indies; Barbados; and Bermuda. 



Beaufort, N. C.: Very abundant on Fort Macon jetties, o to 75 cm. below low tide; extremely 

 abundant on Shackleford jetties and breakwaters, o to 1.2 m.; fairly abundant in harbor, June to October; 

 one battered specimen on Fort Macon jetty, December, 1908. 



The species here described has often been wrongly referred to P. pavonia J. Ag. or to P. durvilkei 

 Bory. From the former it is distinguished by the arrangement of the sori, which are in one or two 

 rows about the middle of each interpilar zone, instead of in single lines on both sides of each alternate 

 piliferous line, as in P. pavonia. From P. durvilkei it is distinguished by the epidermal cells, which 

 are usually about half as long as the central cells, whereas in P. durvillaei they are, in all specimens 

 observed by the author, about one-fourth as long as the central cells. Occasionally those of P. vickersi& 

 are as long as the central cells, the two surfaces of the same section sometimes varying in this respect 

 (fig. 22 and PI. CXIV, figs. 1-3), while those of P. durvilkei are said to be half as long as the central 

 cells. In any case, however, the epidermal cells of the present species are about twice as long, com- 

 pared with the central cells, as those of P. durvilkei. In surface view the epidermal cells of P. vickersioe 

 are rectangular, having a length of two or more times their width, while those of P. durvilhzi are usually 

 about square. The latter species is also coarser and thicker than P. -vickersice, sections showing six 

 cell layers throughout most of the lamina and ten cell layers near the base. 



The present species was first figured by Kuetzing (1859, Bd. 9, p. 30, pi. 73, f. 2) under the name 

 Zonaria variegata, with the reference "Ag- spec. I. p. 127." This, however, refers to the true Zonaria 

 variegata Mertens, whereas the plant figured by Kuetzing is a Padina. Miss Vickers (1905, No. 66) names 

 this species P. variegata with the reference "Zonaria variegata Kuetz." Even if the rules of nomen- 

 clature allowed the recognition of a Zonaria variegata of Mertens and another of Kuetzing, the name P. 

 variegata is rendered invalid by the fact that neither Kuetzing nor Miss Vickers published a description 

 of the species. The citation of Borgesen (1914, p. 205 [49]) to P. variegata (Lamouroux) Hauck seems 

 even less warranted. According to Howe (1915, pp. 49-50), Dictyota variegata Lamouroux seems, from 

 both the published figures and the extant specimens of Lamouroux, to have been exclusively Zonaria 

 variegata. Hauck 's use of the name Padina variegata is merely an incidental mention and is founded 

 only on a reference to Kuetzing. For both of these reasons this use of the name does not seem to con- 

 stitute valid publication. In view of these facts, it has seemed necessary to give a new name to the 

 species. 



Our species, however, approaches very near to P. dubia Hauck (1887, p. 45) and may be identical 

 with this. In Herb. Hauck there are four good unmounted specimens of P. dubia with a loose label 

 written by Hauck. In habit, size, and number of cell layers they resemble the present species; the 

 sori are often irregularly sdattered over almost the entire surface but in parts are in regular zones just 

 above each piliferous line. The available material has not been sufficient to determine whether the 



o The author is gratefully indebted to Dr. Marshall A. Howe for permission to quote from his notes on P. dubia as found in 

 Herb. Hauck, as well as for the opportunity to study portions of two of the original specimens of this species. 



