98 Howe : Phycological studies 



nearly parallel or flexuose and interwoven, subcylindrical, spar- 

 ingly dichotomous, strongly constricted just above the dichotomies, 

 46-84 n in diameter, enclosed in a non-porose calcareous sheath 

 especially in the outer parts, or irregularly incrusted, the super- 

 ficial (or the interior wherever they touch the surface) thickly 

 beset externally with short cylindrical, truncate-conical, subturbi- 

 nate, or obconical processes 16-40 //in diameter, each crowned with 

 2-8 acuminate prongs or spines formed by 1-3 close-set dichot- 

 omies, these lateral processes (mostly 55-160// long, including 

 their spinulose crowns) forming an imperfect kind of cortex ; 

 medullary filaments of the stipe 70-1 10// in diameter, the lateral 

 corticating branches 4-6 times dichotomous, their ultimate divis- 

 ions taper-pointed, mostly 28-200// long and 8-24// in median 

 diameter. [Plate 4, figure 2 ; plate 8, figures 1-7.] 



Collected on a sandy bottom near low-water mark in Bernini 

 Harbor, Bahamas, Hoive J2y2, April 17, 1904. 



Udotea spinulosa is most closely allied to Udotea Palmctta 

 Decaisne,* but is sufficiently distinguished, we believe, by the 



* Udotea Palmetta Decaisne was misinterpreted and wrongly described by J. 

 Agardh, who apparently never saw an authentic specimen of it, and his conception of 

 the species has been adopted by most of the later writers who have referred to it, 

 though A. & E. S. Gepp have seen the type specimens and have recently published 

 critical notes upon them (Trans. Linn. Soc. Bot. II. 7 : 175. 1908). The type in the 

 herbarium of the Museum d'Histoire Naturelle in Paris is represented by two plants 

 accompanied by a loose label, on the bottom of which is printed " Herbier Du Petit- 



Thouars." This label is inscribed in ink " H,^?^^* P^^n^etta D°%" ^^^ u jje^aisne 



l*labe)laria 

 scripsit" has been added below in pencil. No locality is given. Decaisne's de- 

 scription was brief, as are also the notes recently added by A. & E. S. Gepp, and the 

 evident types are therefore described in a little more detail below : 



Udotea Palmetta Decaisne, Ann. Sci. Nat. II. 18 : 105. 1842. 



Plants 5.5 cm. high from a subterete or fusiform rhizoidal base, albescent, much 

 calcified throughout ; stipe simple, subterete, about I cm. long, I-4 mm. wide, its sur- 

 face minutely velutinous (nearly smooth under low magnification) ; flabellum orbicular 

 or obovate, 4.2-4.8 cm. long and of about equal width, 0.09-0.16 mm. thick, rounded 

 or subcordate at base, rather indistinctly and closely zonate (about 16 zones in 4 cm.), 

 plane, longitudinally striatulate, soft and flexible, margins erose or shortly lacerate, the 

 surface appearing strigulose or very minutely pulverulent-punctate under a lens : fila- 

 ments of the flabellum in 3-5 layers, flexuose and interwoven or somewhat parallel, 

 sparingly dichotomous, sometimes slightly constricted above the dichotomies, 22-30 /^ 

 in the major diameter, the superficial more or less flattened laterally (?. e. in a plane 

 perpendicular to the surface) and often only 8-16// in the minor diameter, all irregu- 

 larly and amorphously incrusted with lime, crested superficially, wherever they touch 

 the surface, with a single or double usually secund series of simple, geminate or once 

 furcate spines or sharp teeth, these 11-30// long, sometimes irregularly curved or sub- 

 uncinate ; medullary filaments of the stipe 19-33// in diameter, the lateral corticating 

 branches 2-4 times dichotomous, the ultimate divisions taper-pointed, mostly 27-80 ;« 

 long and 8-1 1 // in median diameter. 



