NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 323 



an apical cell, without a midrib but with many longitudinal microscopic 

 veins; tetrasporangia tripartite, arranged in small, round sori, regularly 

 spaced over the blades ; sori arising as blisterlike swellings from both sides 

 of the frond, the tetrasporangia developing successively from the enclosed 

 sporiferous tissue and remaining in the enlarging sorus until maturity of 

 the tetrasporic fronds; cystocarps unknown. 



Type : Polyneurella Hancockii. 



The type species differs from any members of the closely related genus 

 Polyneura in the mode of branching from the basal axis system, in the 

 entire margins of the blades, and in the absence of a macroscopic midrib 

 in the multiple-vein system. 



Polyneurella Hancockii sp. nov. 

 Plate 47, Figs. 1, 2 



Frondes usque ad 6.5 cm. altae, laminis curte stipitatis, integris, ovato-lanceo- 

 latis e disco parvo compositae; axibus semiteretibus copiose e disco prope com- 

 positis; laminis in partibus juvenis monostromaticis, cellula apicali provisis, eco- 

 statis, venis microscopicis multis. 



Plants to 6.5 cm. high, composed of numerous short-stipitate, entire, 

 ovate-lanceolate blades 2.5 cm. wide, 5 cm. long when mature arising 

 from a small discoid holdfast ; branching of the semiterete axis abundant 

 just above holdfast; blades monostromatic in younger parts, growing by 

 means of an apical cell, without a midrib but with many microscopic 

 nerves, some macroscopic in older fronds ; tetrasporic sori scattered over 

 blades, each bearing 100 or more tetrasporangia; cystocarps unknown. 



Type: D. 184, dredged in 22-44 meters, Puerto Refugio, Jan. 28, 

 1940. Herb. AHF no. 58. 



Genus MYRIOGRAMME Kylin 



Myriogramme divaricata sp. nov. 



Plate 47, Fig. 5 



Frondes usque ad 3 cm. altae, membranaceae, basim 1 mm. soHdo stipitatae, 

 per adhesionem parvam semirhizoideam affixae, tantum in partibus infimis pro- 

 liferatae, abrupte divaricatae, ecostatae, segmentis latis, curtis, avenosis, mono- 

 stromaticis; axillis segmentorum rotundis, non angularibus; marginibus apicalibus 

 multilobatis; crescentione e marginibus apicalibus, cellula apicali deunte; tetra- 

 sporangiis in soris parvis per partes medias et superas laminarum sparsis. 



Plants to 3 cm. high, membranous, from a small, semirhizoidal hold- 

 fast below a solid, stipitate base 1 mm. or less in extent ; fronds proliferous 

 only from lowest parts, abruptly divaricate, lacking a midrib, with broad, 

 short, veinless, monostromatic segments; axils of segments rounded, not 



