292 University of California Publications. | ZOOLOGY 
themselves to the margin of the zocecia of a lower frond. The 
lamine are sometimes united back to back, but are easily sep- 
arable, their union being effected by means of short fibres. 
This species occurs sparingly on the Alaska coast; in Puget 
Sound in considerable abundance; to some extent on the coast 
of California as far south as San Francisco. 
35. Flustra membranaceo-truncata Smitt. 
Pl. XV, figs. 93, 94. 
Flustra membranaceo-truncata Smitt, 1867, p. 358, Pl. XX, 
figs. 1-5. 
Zoarium composed of a number of erect, unilaminate fronds 
(fig. 93). Zoecia irregularly quadrangular, truncate above and 
below, often narrowed below (fig. 94); armed with a delicate 
spine (sp.) at the distal corners; aperture occupying the whole 
of the front; operculum (op.) semicireular. Avicularia (av.) 
sparingly developed, in place of a zocecium; mandible semicir- 
cular, directed upward. Oacia (oe.) small, immersed, not quite 
as wide as the zocwcium against which each projects. 
This appears to be the species which Smitt (67) describes 
and figures, and which he finds in Arctic Seas growing on ascid- 
ians, sertularians, ete., either creeping or erect. The material 
in this collection consists of a few small erect fronds obtained at 
Pribilof Islands, Bering Sea. 
University of California, 
Berkeley, February 15, 1905. 
