Udotea Lamouroux. 



Thallus tipes and frond, with or without a root-mass. 



Rooi composed of a few fairly straight, simple, thick fila- 



ment "i repeatedly forked, tapering root-hairs, looselj interwoven. 



onally divided above, either monosiphonous and bearing .1 few rhï- 



upon the root-mass and composed of numerous branched filaments, which 



are ' en and bear lateral appendages; peripheral endings of the lateral appen- 



• igether to form a cortex which is thickly calcified. 



Frond either monostromatic and simply flabellate, or bi- to pluri-seriate and flabelliform 

 or rarely infundibuliform, simple, lobed <>r proliferous, sometimes crispato plicate, often concen- 

 trically and longitudinally striate, deep-green to ashy-white, varying in thickness and 



calcification. 



Filaments of frond branched dichotomously, occasionally trichotomously, all more or 

 parallel, or parallel in obliquely crossing layers; often bearing numerous papillae, or lateral 

 appendages (<>r branchlets). Appendages unilateral, distichons, subverticillate, or irregularly 

 distributed, occurring in the form of r) acute or truncate papillae, 2) spines, sessile or stalked, 

 simple or more or less furcate, with acute apices, or 3) stalks bearing simple or lobed or 

 cymoidly branched capitula. Cortex, when present, composed of the approximated or contig- 

 uous apices of the lateral appendages, and encrusted with linie. Calcareous sheath of frond- 

 filaments porose in those species which are destitute of lateral appendages. 



The following characters are of prime importance in the discrimination of the species: 



1 . Structure of frond : 



a) W'hether monostromatic or pluriseriate. 



Whether the filaments bear lateral appendages or not. 

 c) The shape and arrangement of the lateral appendages. 



Whether the filaments are unevenly or evenly constricted above the dichotomies. 

 e) The diameter of the filaments. 



2. Structure of the stipes, whether monosiphonous or compound. 



The following Key is based upon a consideration of the above characters. 



Key t o the species. 



A. Main filaments visible in surface view, when magnified about 

 50 diameters. Frond often fissile. 



a. Frond monostromatic. Filaments parallel, laterally coherent. 

 i-j. Filaments of frond without papillae. 



1. Plant small. about 1 — 2 cm. high. Stipes always mono- 

 siphonous. Filaments of frond \o 50^ thick . . . 1. I '. javensis (p. 1 10). 



2. 1'iant larger, up to g cm. high. Stipes compound, 



ticated. Filaments of frond 6 \ or more) thick. 3. U. glaucescens (p. m ;, . 



