Fostig AND Howe: NEW CORALLINE ALGAE 579 
Lithophyllum Antillarum Fosl. & Howe, sp. nov. 
Thallus grayish-pink or decolorate when living, becoming 
pallid or greenish-pallescent on drying, forming often somewhat 
columnar rather flat-topped masses 10-30 cm. high and 8-20 cm. 
broad ; branches much fused, forming in the basal parts an almost 
solid mass with more or less lacunae, the irregular and somewhat 
daedaleoid anastomoses extending nearly to the irregularly pyram- 
idal, somewhat prismatic, subconical, compressed or occasionally 
subterete, often truncate or retuse apices, the free portions mostly 
5-25 mm. broad and 3-12 mm. thick, often enlarging upward, 
the interstices commonly tubular or irregularly infundibuliform ; 
surface smooth or subpulverulent, or, especially at the sides, 
minutely corrugated or rugulose; medullary hypothallic cells 
7-18 # x 7-10 4, sometimes forming (in a longitudinal section) 
regularly alternating rows of one short and two long cells ; peri- 
thallic cells subquadrate or roundish, 7-10 » in diameter ; short 
rows of larger cells (20-33 4 x 14-20 yp) occurring here and there 
in both medulla and perithallium : conceptacles of sporangia con- 
vex, but little prominent, 150-300 in diameter: sporangia 4- 
Parted, 38-70 4 x 20-40 . (FIGURE 2 and PLATES 25, 26.) 
Growing at low-water mark on a coral reef at Flamingo Bay, 
Culebra Island, Porto Rico (M. A. Howe, 7 March 1906, 10. 4373). 
a CRAY 
mer ty) 
Ficure 2, Lithophyllum Antillarum ; a, portion of surface with tetrasporangial 
fonceptacles, > 5; 4, portion of a radio-vertical section, showing row of enlarged ; diz 
X 232 (the cells should be more rounded at the angles, as indicated in photomicro- _ 
Staph, PLATE 26); ¢, tetraspores, < 150. 
Lithophyllum Antillarum is evidently a reef-builder. In general 
abit it bears some resemblance to coarse forms of Lithophyllum 
Yricanum Fosl. (Cape Verde) and to well-developed conditions of 
Lit phylum craspedium Fosl., a species originally described from 
*Pecimens brought from Funafuti and since discovered in the 
Maldives (see Fauna and Geography of the Maldive and Laccadive 
a Archipelagoes, I: pl. 25. f. 7). It is perhaps the more closely 
ee elated to the latte 
a to the Possession of the peculiar short rows of enlarged cells 
r species, agreeing essentially in structure even 
