380 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



Howe, 1909, p. 89, PI. VI, figs. 13-15: PL VII, figs. 1-4. 

 Stipe 1-3 mm. high, disk solitary, nearly flat, 1-2.5 mm - diam., 

 rays 6-17, usually 11-15, obovoid-clavate to clavate-subfusiform, 

 blunt or obtusely taper-pointed, easily separable ; corona supe- 

 rior 22-35 /" diam., with 2, rarely 3 hair-scars ; aplanospores 

 15-60 in a sporangium, 68-82 /A diam. W. I. 

 The smallest of our species, and quite lightly calcified. 



2. CHALMASIA Solms, 1895, p. 32. 



Disk terminal, composed of rays united only by the incrusta- 

 tion ; corona inferior wanting ; segments of the corona superior 

 not touching laterally ; aplanospores free, with thick, much cal- 

 cified membrane. Only one species. 



C. ANTILLANA Solms, 1895, p. 32, PL III, figs. 2, 3, 5. Disk 

 funnel-shaped, 6 mm. diam., rays 25-32, covered with a thin, 

 easily detachable incrustation, and not otherwise united, vesic- 

 ular and inflated ; aplanospores globular, chalk-white ; hair- 

 scars 2-3. Fig. 140. 



In habit quite like a small Acetabularia crcnnlata, but suffi- 

 ciently distinct in the spore characters. The only known speci- 

 mens were dredged at some point, not definitely known, off the 

 Florida coast. 



3. ACICULARIA D'Archiac, 1843, p. 386. 



Rays of the disk united, corona superior and corona inferior 

 present ; interior of the ray ultimately occupied by a calcareous 

 mass enclosing uncalcified aplanospores. 



The genus was founded by the paleontologist D'Archiac in 

 1843, on certain minute spicules found in the Eocene formation 

 in France ; two or three other fossil species have since been 

 recognized, but only one living species is known. 



A. SCHENCKII (Mob.) Solms, 1895, p. 33, PL III, figs. 4, 9, 

 n, 12, 14, 15. Stipe 1-3 cm. high, thin-walled, rather stout; 

 disk 6 mm. diam., flat or nearly so, with crenulate margin; 

 rays 30-50, fairly closely united, wedge-shaped ; corona superior 

 13 mm. diam., with 2 hair-scars to each ray; aplanospores 

 100-200 in a ray, globose, 60-80 /x diam. From literal to 30 m. 

 depth. Bermuda, Martinique, Guadeloupe. So. America. 



4. NEOMERIS L-amouroux, 1816, p. 241. 



Frond cylindric-clavate, more or less strongly calcified, con- 

 sisting of a simple, inarticulate axis, attached by lobed or 

 branched holdfasts, and bearing thickly set, uniform whorls of 

 12-80 primary branches, each branch except those of the lower 

 whorls bearing a terminal short-stiped sporangium, and two 



