VoL. 2 | Robertson.—Non-Incrusting Bryozoa. 253 
farther south, slightly less. In the main points, however, the 
Menipeas from these various localities strongly resemble each 
other and in no points more constantly than in the position and 
form of the chambers from which the root and climbing fibres 
spring. 
6. Menipea gracilis Busk. 
Pl. VI, figs. 18, 19, 20, 21. 
Menipea gracilis Busk, 1881. 
Menipea ternata, forma gracilis, Smitt, 1867. 
Zoarium forming a loose, tangled mass due to the great num- 
ber of tendril-like fibres which twine around neighboring 
branches. (PI. VI, fig. 18.) Branching dichotomous; internodes 
consisting of three zocecia, except terminal internodes and those 
possessing ovicells, which may have five, seven, or nine zoceeia; 
internodes of three zowcia only, often very long, ranging from 
1,600 to 1,900 » in length. Zoawcia enlongated, aperture large. 
(fig. 19). Zocecia with two or three spines, depending upon 
the presence or absence of the lateral avicularia. If the latter 
are absent there will usually be two spines on the outer margin; 
if present, then but one (sp.). There is always a spine on the 
inner margin of the aperture just above the seutum. Zocecium 
at bifurcation possesses one or two spines, more often one, at 
its summit. Scutwm (sc.) large, flabellate, projecting outward 
and arching over the aperture in well developed specimens, pro- 
jecting beyond the outer edge of the zoecium. Lateral avicularia 
frequently absent, when present often minute. Frontal avi- 
cularia (fr. av.) oceur on the zocecium at the bifurcation of the 
branch, but these too, are frequently absent; on ocecial inter- 
nodes,. however, they are often found on each zocecium, situated 
a little to one side of the aperture and so close to the owcium 
as to seem perched upon its upper margin (fig. 20, av.). 
Oacia (oe.) high, rounded, with striations radiating from a 
thin place at the base of the owcial wall. Rootlets originating 
at two places. Those which anchor the colony springing, as a 
rule, from a disk to one side and below the aperture (fig. 19, 
r. d.) ; the others, more tendril-like, and for the most part ex- 
