278 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



DELESSERIA Lamouroux, 1813 

 Thallus foliaceous, branched, of one cell layer except for the veins, 

 showing both midribs and macroscopic or microscopic side veins; branch- 

 ing through proliferation from the midribs, vi^hich in section show scat- 

 tered rhizoids between the larger cells of the central portion ; structurally 

 showing a prominent apical cell which divides transversely, not all cells 

 of the third order maintained at the thallus margin, and intercalary di- 

 visions present in the cell rows of the second and higher orders; tetra- 

 sporangia and spermatangia in sori between the veins ; procarps with one 

 carpogenic branch, the gonimoblasts with spores in chains, the pericarps 

 prominent, situated on the veins. 



Delesseria Hancockii n. sp.^^* 

 Plate 90 



Plants to 85 cm tall, below denuded to a firm slender stalk which is 

 very sparingly branched, above bearing a few large rose-colored blades 

 15-25 cm long which near their bases gradually break down, but are in 

 general broadly oblong lanceolate, to 7 cm wide, rather obtuse at base 

 and apex, the margin somewhat uneven to undulate; with pinnate vena- 

 tion, the midrib showing large and small cells intermixed in the central 

 tissue, prominent to the apex and developing somewhat obliquely sub- 

 opposite side veins at intervals of 3-7 mm, which are quite straight and 

 visible to the unaided eye for about the first third of their length, and 

 which can be traced with the microscope along a more irregular course to 

 within a short distance of the margin, where they disperse in obscure 

 wandering microscopic veinlets ; branching of the frond originating from 

 the face of the midrib; blade of one cell in thickness, except in the region 

 of the veins and major veinlets; tetrasporangia in very numerous small 

 scattered irregular sori about 0.2-0.5 mm diam. which occupy the blade 

 area between the veins of the outer three fourths of the width of the leaf. 



This large and handsome plant appears to be very different from any- 

 thing described hitherto. It is broader and has more prominent veins than 

 D. lancifolia, and the distribution of the tetrasporangia seems to be distinc- 

 tive. 



Ecuador: Archipielago de Colon, rare as dredged off Academy Bay, 

 I. Santa Cruz, no. 34-306 (tetrasporic, TYPE), 20 Jan. 1934. 



174 Delesseria Hancockii n. sp. — Planta ad 8.5 dm altitudine, stipitem sparse 

 ramosum tenuemque et laminas paucas, oblongo-lanceolatas 15-25 cm long., ad 7 

 cm lat. habens; laminis in basi apiceque obtusis, margines subundiilatos, costam 

 perspicuam, venas laterales pinnatas suboppositasque, intervallis 3-7 mm, habenti- 

 bus; tetrasporangiis in soris multis, dispersis, 0.2-0.5 mm diam., qui superficiem 

 laminae inter venas partis 54 externae folii occupant. Planta typica in loco dicto 

 I. Santa Cruz, Ecuador, legit W. R. Taylor no. 34-306, 20 Jan. 1934. 



