1925] Setchell-Gardner : Melariophyceae 661 



strichus structure. Z. Biesingiana J. Agardh is more prostrate and 

 coarser. The Japanese plant illustrated under this name by Okamura 

 (1907, pi. 4, figs. 1-10) has paraphyses with peculiar swollen terminal 

 cells. Zonaria interrupta (Lamour.) J. Agardh, from the Cape of 

 Good Hope, has very narrow divisions and has paraphyses with short, 

 swollen cells above, as in ours, but the terminal segment of each divi- 

 sion of the frond is peculiarly truncate and enlarged above (cf. 

 Phycopteris cuneata Kuetz., Tab. Phyc, vol. 9, 1859, pi. 67, fig. II). 

 The structure of the frond is also very different, as may be seen from 

 Kuetzing's figure quoted above. 



61. Padina Adans. 



Fronds plane, ecostate, flabellate, entire or branched, differentiated 

 into two kinds of tissues, a single surface layer on either side consist- 

 ing of color bearing rectangular cells, and a central tissue, medulla, of 

 several layers of somewhat elongated cells with few chromatophores ; 

 growth in length by divisions of many marginal cells ; margin scrolled, 

 or inrolled ; reproduction sexual, heterogamous, and asexual by aplano- 

 spores ; the reproductive organs at times developed in transverse zones 

 on the upper parts of the fronds and the antheridia in longitudinal 

 sori, on the same frond as the oogonia. 



Adanson, Fam. II, 1763, p. 13 (fide De-Toni). 



The " Peacock 's-Tail" algae are well-known tropical species whose 

 specific limits require careful study and consideration. The genus is 

 readily distinguished by its involved meristematic margin and by its 

 having the sori only on one side (the upper) of the frond. 



Padina Durvillaei Bory 

 Plate 93 



Fronds 10-22 cm. high, membranaceous to decidedly coriaceous, 

 highly stupose for considerable distance above the base, repeatedly 

 and irregularly branched by splitting of the blade more or less deeply, 

 the lobes laciniate to reniform-flabellate ; thickness of frond varying 

 from 18 cells, at the base, to 1 cell, at the broad inrolled margin, for 

 the most part 8-12 cells thick ; the flabellate portion of the frond 

 marked distinctly by numerous, narrow, concentric bands of hairs; 

 color dark brown, dark green to almost black on drying; sori of 

 oogonia and aplanosporangia distributed unevenly over both sides of 



