112 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



to prefer to follow the intercellular cavities between the cortex 

 and medulla; they are sometimes closely associated with the 

 endophytic filaments of the Streblonema solitariiim, but may be 

 distinguished by their smaller diameter and shorter cells. 



Elackistea stelliilata was first described from southern England 

 but has since been reported also from France and from Ireland. 

 Its presence in American waters has not hitherto been noted, so 

 far as we know. 



Erythrocladia recondita sp. nov. 



Endophytic or pseudo-epiphytic, creeping in the superficial cell 

 walls of other algae; thallus consisting at first of free irregularly 

 radiating and irregularly branching filaments, soon becoming 

 more or less pseudoparenchymatous (essentially monostromatic) 

 in central parts, at length irregularly suborbicular and attaining a 

 diameter of 0.2-1.5 mm., or sometimes apparently broader through 

 confluence; ramification lateral or subdichotomous, the lateral 

 branches, especially in the younger plants, often divaricate; cells 

 (protoplasts) varied and irregular in form, in surface view mostly 

 oblong, quadrate, ovate, or panduriform, often curved, forked, 

 or irregularly i- or 2-lobed, 8-25 /x long, 3-12 ix broad; pyrenoids 

 1-4 (usually I or 2), commonly 2.0-3.5 M broad and consj^icuous; 

 monoecious; spermatia ovoid, 2-4/1 in diameter, exserted or sub- 

 exserted by slender stalks about i 11 broad; carpogonia furnished 

 with a beak or trichogyne exserted about 4-8 ^i; sporocarps forming 

 a single carpospore (or rarely 2), these ovoid, oblong, or irregular, 

 mostly 8-19 /i in maximum diameter; non-sexual spores unknown. 

 [Plate 12, figures 1-5; plate 13, figure i.] 



In the superficial cell walls of Dictyota dichotoma, Beaufort, 

 N. C, W. D. Hoyt, September 7, 1906 (type) — associated with 

 Acrochaetium Hoytii; also on September 14, 1906, in smaller 

 quantity and less well developed; also in Dictyota dichotoma and 

 other algae and in stolons of hydroids, "in 13^^-14 fathoms," 

 on reef 23 miles from Beaufort, Lewis Radcliffc, August 11, 1914. 



In its earlier stages of de\-elopmcnt, Erythrocladia recondita 

 bears some resemblance to E. irregularis Rosenvinge,^ described 

 from Danish waters on Polysiphonia tirceolata, but it difTers from 

 that species in being larger in all its parts (thallus finally 0.2-1.5 

 mm. vs. 100 /x broad; cells 8-25^1 X 3-12 /x vs. 7-I1 jj. X 3.5- 

 5.0 /x), in its more conspicuous pyrenoids, and in its sexual mode 



1 Kgl. Danskc X'iflcnsk. Sclsk. Skrifl. VII. 7: 72./. //. 12. 1909. 



