494 BULLETIN OF THE BUREAU OF FISHERIES. 



KEY TO GENERA. 



Frond usually dichotomously or pinnately branched, midrib inconspicuous or lacking, 

 veins, when present, usually forming a network over the thallus i. Nitophyllum (p. 494). 



Frond usually simple, sometimes irregularly branched, midrib conspicuous below, veins 

 usually not visible to naked eye, arising pinnately from the midrib 2. Grinnellia (p. 495). 



Genus i. Nitophyllum Greville. 

 Nitophyllum, Greville, 1830, p. 77- 



Thallus flat, thin-membranaceous, sessile or borne on a short stalk, simple or 

 dichotomously branched or lobed or divided in various ways, veins present or absent, 

 if present more or less prominent, sometimes elevated, much branched and usually 

 anastomosing, sometimes more prominent, branched, usually anastomosing nerves and 

 occasionally a slight midrib also present; composed of one or a few layers of cells, outer 

 cells large and irregularly angular in surface view, squarish or oblong in section, cells of 

 inner layers sometimes different from the outer ones, veins and nerves composed of 

 several layers of narrow, elongated cells; apical cell evident in the young frond, some- 

 times persistent for a while, but sooner or later disappearing, the growth of the adult 

 frond being intercalary; tetrasporangia triangularly divided, occurring in sori forming 

 rounded, flattened thickenings prominent on both surfaces of the frond, variously situ- 

 ated in different species; cystocarps scattered over the frond, variously situ- 

 ated, sessile, prominent on both surfaces of the thallus, rounded, slightly flattened, 

 opening by an apical pore, gonimoblast arising from the base of the cavity, composed of 

 radiating, branching, segmented filaments more or less compacted into lobes producing 

 carpospores singly or in short chains from their terminal segments. 



About 75 species, in warm and temperate seas. 



Nitophyllum medium sp. nov. Fig. 35; PI. CV; PI. CXIV, figs. 4 and 5. 



Thallus erect, flat, ribbonlike, borne on a (usually short) more or less definite stipe, 5 to 22 cm. tall, 

 4 to 19 mm. wide, decompound-dichotomously branched, margins usually undulate, often bearing 

 minute proliferations; veins numerous, sometimes conspicuous, sometimes invisible to the naked eye, 

 repeatedly branched, subsingle toward apices, anastomosing frequently throughout most of thallus, 

 coalescent below into stipe ; thallus composed of a single layer of cells except at margins and in regions 

 of sori and veins, margins irregularly more or less thickened, sori usually surrounded by more or less 

 extensive regions three cells thick, veins three to five (rarely six) cells thick, usually one (rarely two) 

 cells wide, sometimes bordered by a narrow region of thallus three cells thick; tetrasporangial sori 

 numerous, small, prominent on both surfaces, borne throughout thallus except toward base, forming more 

 or less irregular (often very irregular) parallel or radiating lines, usually between the veins; antheridia 

 and cystocarps unknown; texture thin-membranaceous; color light pink to rose. 



Thallo erecto, piano, plus minus definite (plerumque breve) stuposa, 5-22 cm. longo, 4-19 mm. 

 lato, decomposito-dichotome ramoso, marginibus plerumque undulatis, saepe proliferationes minutas 

 ferentibus; venis numerosis, nunc manifestis, nunc oculo nudo invisibilibus, iterum atque iterum 

 ramosis, ad apices subsimplicibus, per maximam partem thalli frequenter anastomosantibus, in in- 

 feriore fronde in stipitem coalescentibus; thallo, praeter margines et regiones sororum et venarum, una 

 pagina cellularum composite, marginibus inaequaliter plus minus densis, sons plerumque ab regionibus 

 plus minus latis, 3 cellulis crassis, cinctis, venis 3-5 (rarius 6) cellulis crassis, plerumque i (rarius 2) 

 cellulis latis, aliquando ab regione thalli angusta 3 cellulis crassa tactis; soris tetrasporangiorum numer- 

 osis, parvis, in superficiebus ambis prominent! bus, per thallum, praeter partem inferiorem positis, 

 lineas plus minus irregulares (saepe irregularissimas) parallelas aut radiantes, plerumque inter venas, 

 formantibus; antheridiis et cystocarpiis ignotis; substantia tenue membranacea; colore diluta punicea 

 aut rosea. 



