306 
non Thugjaria plumulifera Nutting, The Sertularidae; p. 67, pl. IX, figs. 
9—13. 
(Pl. V, figs, 1—6). 
The colony is provided with an extremely thin and slender 
stem, divided into distinct internodes, each of which bears a branch, 
but while a number of the proximal branches are alternate, simple, 
and rather short (length 8—10 mm), the rest of the branches, 
which are børne by very long internodes, are spirally arranged, much 
"longer (19—30 mm) and each provided with 4—7 pairs of alter- 
nate branchlets. Their axes are like the main-stem divided into 
distinct internodes, a few of which may be without: branchlets. 
The hydrothecae, which are provided with a convex ad- 
cauline and a somewhat concave abcauline lateral margin, are 
turned outwards and more or less frontally, but in opposition to 
what is the case in H. falcata (Pl. V, fig. 8) not only their distal 
ends, but also their bases are in the single branchlets arranged 
into two distinct longitudinal series, and the single hydrothecae 
of a branchlet either do not touch each other at all or only in a 
very small degree, a small proximal and adcauline portion of a 
distal hydrotheca being in connection with or covered by ”a proximal 
one. For the rest they are very like those of H. falcata, and 
their distal fourth is freely' projecting. 
The distance between the hydrothecae of the two series as 
also their direction varies according to their place in the branchlet, 
in such aåa way that the more proximally the hydrothecae are 
placed the greater is the distance between the two series, and the 
less distinet is the frontal turning of the hydrothecae. Å corres- 
ponding difference is also contingent upon the more or less proximal 
or distal position of the branchlet in the branch, and of the branch 
in the stem, and, therefore, the distance between the two series 
of hydrothecae attains its maximum in the proximal part of the 
proximal branches, and here the frontal turn of the hydrothecae 
— is almost imperceptible. A line dividing one of these branchlets 
into two lateral halves, in the distal end only cuts off a small 
