1910] Robertson: Cyclostomatous Bryozoa. 239 



This species occurs between tide marks in company with other species 

 of Crisia at Fort Point and Lands End, San Francisco; at Deadmans 

 Island, San Pedro, and at La Jolla, California. It has also been obtained 

 between tide marks at Sitka, Juneau, Yakutat, and Orca, Alaska; and at 

 low tide on Channel Rocks, Puget Sound. Dredged also off San Diego in 

 depths ranging from 16 to 30 fathoms. 



87. Crisia occidentalis Trask. 



PI. 19, figs. 11, 12. 

 Crisia occidentalis, Trask, 1857, vol. I, p. 113, pi. V, fig. 4. 

 Crisia eournea, Robertson, 1903, p. 116. 



Zoaria forming dense tufts whose branches curve inward 

 especially in those colonies bearing ovicells; colonies from 20 to 

 2r)inni. in height (pi. 19, fig. 11), growing on seaweed, on rocky 

 ledges, on other bryozoa, attached by numerous jointed rootlets. 

 Internodes in the lower and older portion of a colony consisting 

 of three, four, or five zocecia ; in the younger and larger portion 

 of the colony seven being the prevailing number, although inter- 

 nodes of nine or more zocecia occur. Branching, as a rule, 

 alternate; usually but one branch in an internode, arising 

 commonly from the third zooecium. Joints light-colored, yellow- 

 in the older parts, white in the younger. Basis rami [ba. r.) 

 except of the first zooecium of an internode, not wedged in. but 

 simply applied to the side of the zooecium from which 

 it originates. Zocecia connate through almost their whole length, 

 somewhat abruptly curved forward at their anterior end, often 

 possessing a pronounced denticle (a 7 .) or projection on the 

 outer side of the aperture. Ocrcia (oe.), tapering at the origin, 

 growing broader somewhat suddenly so that the upper two- 

 thirds is of the same diameter throughout; the third, fifth, or 

 seventh member of its internode; adnate to its dorsal surface 

 are several zocecia, often four, one of which, the fifth, seventh, or 

 ninth, depending upon the place in the series occupied by the 

 ou'ciiuii (see page 2:i(D. extending above it, curving forward, and 

 opening beside the oceeial aperture. Oceciostome smaller in 

 diameter than the aperture of a zooecium, opening a little below 

 the apex of the ovicell on the dorsal side; tube of oceciostome 

 short, but rising above the summit of the ovicell, delicate, hyaline. 

 Oceciopore (oep.) circular, opening directly upward. 



