bo 
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University of California Publications. [ ZooLocy 
to 35 mm. high and from 60 to 80 mm. broad (Pl. V, 
figs. 12, 13). Branching dichotomous. Internodes consisting of 
three zocecia, as a rule, although there are many instances of 
five or seven zoccia to an internode. The longer internodes are 
generally terminal and bear the ovicells. Joints light colored, 
arising in distinct tubes (fig. 14, j.). Zoacia elongated, narrowed 
below; aperture oval (ap.), occupying less than half the front, 
with two or three spines, one on the inner margin just above the 
operculum, and one or two on the upper, outer margin; zoccium 
at bifureation of branch having sometimes one, sometimes two 
rather long spines at its summit. Towards extremity of branches 
the spines increase in length, often very considerably. Scutwm 
varying in shape from a mere spine to a somewhat broad flabel- 
late process (sc.). Lateral avicularia (av.) large, and promi- 
nent, generally developed on all the zocecia of an internode 
except the one at the bifurcation of a branch; sometimes. how- 
ever, missing. Frontal avicularia (fr. av.) on the zocecium 
at bifurcation only; small, raised, with mandible directed for- 
ward, often obliquely to right or left. Oacia smooth, somewhat 
elobose, reaching not quite to the lower margin of the next upper 
zocecium (oe.). From a flat disk in front or to one side of the 
aperture of many of the lower zoccia in a colony, root fibers (7.) 
extend downward, assisting in anchoring the colony to the sub- 
stratum; from zocecia higher in the colony other upward ex- 
tending fibres arise in a dorso-lateral chamber (7. ch.) which is 
slightly raised and which projects from the zocecial wall. 
M. ternata is widely distributed, being found on Channel 
Rocks, and San Juan Island in Puget Sound; and at Dillons 
Beach, Lime Point, Mendocino, and Lands End on the coast of 
California. It is also reported by Hincks from Queen Charlotte 
Islands. 
In the species from these different localities considerable 
variation occurs. As a rule, the colonies from California grow 
in more compact masses, and the triads of zocecia forming the 
internodes are shorter than are those of the Puget Sound species. 
Thus the length of an internode in the Puget Sound species 
varies between 1,100 and 1,500 p», and that of the species found 
