G. W. Lee — Trepostomatci. 
153 
YI.— Descriptions of Species. 
Genus Stenopora Lonsdale. 1 
Stenopora redesdalensis sp. nov. 
Plates XIV, fig. 5 A—5 D ; XY, figs. 1, 2. 
1881. M onticulipora ( Heterotrypa ) tumida Nicholson. On the Structure and 
Affinities of the Genus Monticulipora and its Sub-Genera, p. 120, plate iii., fig. 1. 
Description. —(a.) External characters. The zoarium is ramose, the branches being 
cylindrical, varying in diameter from 2 to 6 mm. The branches assume either the solid 
or the hollow mode of growth, the two forms being equally common. The branching 
usually takes place in one plane, more rarely in more than one plane. 
Maculte of small, thick-walled cells, are common. No monticules have been 
observed. The zooecia-apertures are circular or sub-polygonal, according to the thickness 
of their partitions. There are some thirty apertures along a distance of 1 cm. The 
acanthopores are of two sizes : fairly large ones are limited to the junction-angles, while 
more numerous but smaller ones occur in a single row between the apertures whenever 
these are separated by thick partitions. 
(b.) Internal structure. Longitudinal sections show that the zooecia are, in the 
centre, parallel to the long axis of the branch and bend gradually outwards until the 
final portion of their course is at right angles to the surface. The zooecia-walls are 
extremely thin from their proximal end to that portion of their course where they 
assume the final change of direction. From that point to their distal end they are 
greatly thickened, the change in thickness being sudden, without transition. The 
thickening of the walls is generally not uniform, but is effected more or less periodically, 
so that most walls, as seen in section, have a roughly moniliform appearance. The 
alternations of the thickening process are not strongly marked and occur at relatively 
long intervals, consequently the beading is much less pronounced than in the more 
typical species of the genus. 
Tabulae are sparsely represented in the axial region and are generally localised in 
the sub-peripheral portion of the tubes, none having been observed in the outer portion 
of the peripheral region. The interval separating them is slightly more than their own 
diameter. They are straight or very seldom concave. 
1 An emended description of the genus is given on p. 148. 
0 2 
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