VoL. 2] Robertson.—Non-Incrusting Bryozoa. 259 
11. Serupocellaria californica Trask. 
Pl. VIII, figs. 35, 36, 36a, 37. 
Scrupocellaria californica Trask, 1857, p. 114, Pl. 4, fig. 2. 
Scrupocellaria brevisetis (?) Hincks, 1882, p. 462. 
Zoarium growing in large compact tufts, somewhat coarse in 
appearance. (PI. VIII, fig. 36a.) Branching dichotomous, inter- 
nodes consisting of five, seven, or nine zowecia. Zowcia shghtly 
attenuated below, aperture occupying more than half the front 
(fig. 36). Two, often three spines on the upper, outer margin 
and one on the inner just above the seutum. Zocecium at the 
bifureation (z@. bi.) of a branch with one short spine at its apex: 
two spines below on one side and one spine on the other just 
above the secutum. Scutwm (sc.) often spine-like, sometimes 
broadened below, and always curved with a downward slope. 
Lateral avicularia generally present, when absent, an extra spine 
may develop in that place, making the third on the outer edge 
of the margin (sp.). Avicularia vary in size, but unlike those 
of the following species, the fluctuation in size lies in the greater 
or less relative proportion of the muscular part (lat. av.). Fron- 
tal avicularia (fr. av.) present on each zocecium just below the 
aperture. Vibracular cell frequently lacking, and not visible 
from the front surface except on the zocecium at the bifurcation 
of a branch (v. c.). Vibracula, when present, found only on 
the zocecia of the lower part of the colony where root fibres are 
given off (r.). This is usually true except of the zocecium at 
the bifurcation of a branch where vibracular cells are generally 
present irrespective of the formation of a root fibre. Vibracu- 
lum shorter than a zocecium; vibracular chamber much like a lat- 
eral avicularium in form (fig. 35, v. ch.). The groove, lying in 
the part corresponding to the lower mandible of an avicularium, 
extending transversely across the dorsal surface of a zocecium 
(gr.), the short stout vibraculum much like the elongated upper 
mandible of an avicularium. Oacia sparingly developed, found 
only on internodes at the extremity of the branches, three or 
four in an internode, smooth (fig. 37, oe.). Rootlets abundant 
on the lower internodes of a colony where vibracular cells abound 
with their short vibracula (fig. 36, 7.). 
