187 
Observations on the Pyrocystece. 
abundance of i\ pseudonoctiluca ), and that, but for the somewhat 
meagre evidence provided by these figures of Schtitt, the Pyrocystcse 
would have to be considered as an algal group of quite unknown 
affinities. 
SYNOPSIS OF SPECIES. 
Pyrocystis—Wyv. Thoms ex J. Murray. 
P. pseudonoctiluca, Wyv Thoms, ex J. Murray, Proc. Roy. 
Soc. Lond. Vol. xxiv. 1876, page 533, pt. xxi, fig. 1. (Syn. P. noctiluca , 
Murray, “Challenger” Report, Vol. I. pt. 2, 1885, p. 935.) 
Cell spherical ; main portion of protoplasm collected at one 
pole; chromatophores, small oval plates ; nucleus elongated. 
P. fusiformis, Wyv. Thoms, ex J. Murray, Proc. Roy. Soc. 
Lond. Vol. xxiv., 1876, page 533, pi. xxi., fig. 2 (Syn. P. fusiformis , 
Murray, “ Challenger” Report, Vol. I., pt. 2, 1885, p. 935.) 
Cell spindle-shaped; main portion of protoplasm central; 
chromatophores, shape ? ; nucleus round. 
P. lunula, Schiitt. Engler and Prantl. Pfanzenfamilien 
Peridin, ex Teil 1. Abt. 1, 1896, p. 3, fig. 2. (Syn. Gymnodinium lunula 
Schiitt, Die Peridineas des Plankton Expedition, Teil I., 1895, pi. 24, 
fig, 80.) 
Cell half-moon shaped; chromatophores mostly short rods; 
nucleus round, central. 
P. hamulus, Cleve, K. Vetensk Akad Handl, vol. 34, No 1. 
1900, pi. vii., fig. 23, (Syn. P. bicornis, Blackmn, Murray and 
Whitting, Trans. Linn. Soc. Lond., 2 nd ser. Botany, vol. 5., pt. 89, 
1899. ) 
Cell two-horned; chromatophores, shape?; nucleus round, 
central. 
P. lanceolatus, Schroder, Mitth Zool. Stat. Neapel., vol. xiv. 
1900, p. 13, fig. 11. 
Cell elongated, pointed at both ends, chromatophores ? 
nucleus ? (This species I have not seen, but there is nothing in the 
figure or few words of description given by Schroder, to distin¬ 
guish it from I\ fusiformis.) 
