578 FosLtice AND Howe: NEW CORALLINE ALGAE 
main harbor of Culebra Island, Porto Rico (M. A. Howe, 3 March, 
1906, 0. 4224). 
Goniolithon acropetum is probably most nearly allied to Goniolt- 
thon frutescens Fosl. f. fabelliformis, of the South Pacific, originally 
described * from Funafuti, but is evidently quite distinct from that 
species, being coarser,t more anastomosed, often much more 
widely dilated, and more conspicuously decutescent ; the con- 
ceptacles of sporangia are somewhat larger (about 1 mm. diameter 
vs. 500-600 fv in G. Srutescens) and are rather less abruptly conical, 
and the sporangia attain larger dimensions (reaching maxima of 
168 # in length and 102 in width vs. 110 and 50 in G. 
Frutescens); the perithallic layer is thicker, and after decalcification 
the cells of both perithallium and medullary hypothallium appear 
more rounded at the angles and firmer-walled than in G. frutescens. 
Conditions of Goniolithon acropetum with subterete branches 
sometimes bear a slight resemblance to forms of G. strictumt Fosl., 
@.? 5 
FIGURE I. Goniolithon acropetum ; a, end of a terete branch showing tetra- 
sporangial conceptacle and exfoliations, 5; 4, tetraspores, < 150. 
but are coarser, less fragile, and have less tapering branches. A 
small form of G. strictum was found growing within half a mile of 
G. acropitum and was always abundantly distinct. 
On the other hand, forms of Goniolithon acropetum with dilated, 
flabelliform branches have a certain superficial resemblance to 
Lithophyllum platyphyllum Fos\. (St. Martin, West Indies) and 
Lithophyllum daedaleum pseudodentatum Fos\. & Howe (Porto 
Rico), but have really no close affinity with either of these. Both 
of the last named forms are either not at all decutescent or flake 
off only minute and irregular scales. 
* Det Kgl. Norske Videnskabers Selskabs Skrifter. No. 1. 1900. 
+ Compare published photographs of G. #frutescens f. typica, in The Fauna and 
Geography of the Maldive and Laccadive Archipelagoes x: p/. 25. f. 4; and in Corl 
inaceae Siboga-Exped. f/. 10. f. 7-9. 1904. 
