512 
PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION 
vegetable and not animal structures. The Traquaria is a spherical organism with a 
thin structureless investing layer or capsule-wall prolonged into numerous radiating 
tubular appendages, which for convenience may be designated spines. The mean 
diameter of the central sphere in eight specimens is '01333, the maximum being '02, 
and the minimum ’01. The interior of the sphere is occupied, in several examples, 
by cells, enclosed within one or more inner membranes, and the entire organism, 
including its spines, appears as if it had been invested by some plastic substance.* 
Since these several parts of the organism exist in various forms in different examples, 
the most convenient mode of describing them will be to examine the more character¬ 
istic individual specimens in detail. 
Fig. 40 represents the smallest specimen I have met with. Though crushed, it is 
valuable, since it shows that, at this stage of its development, both the capsule-wall, 
a, and the spines, b, were free from brittleness, having been flexed by the pressure to 
which they have been subjected, but without breaking. The plastic (?) investment is 
seen at e, as a faintly granular element devoid of any very definite outline. At b', a 
portion of the outer capsule-wall has got displaced, revealing sections of three spines, 
and the entire extent of this tissue exhibits numerous circles and parts of circles 
shortly to be explained. Fig. 41 represents a fine example of which the central 
sphere, a, has been intersected a little on one side of its maximum diameter, the latter 
being shown at the circumference, a', of the dark ring. The outer capsule-wall is thus 
seen obliquely and exhibits numerous small rings. The spines, b, are here more rigid 
than in fig. 40. They have yielded to pressure, but at b', b', b' they have done so less 
readily than in fig. 40—hence they have been thrown, at the yielding points, into more 
angular forms than seen in the curved ones of that figure. Each spine is broadest at 
its base, and is muricated externally throughout its entire length, but these muricated 
projections become more sharp and prominent as we pass from the basal to the free 
extremity of each spine. The murications are arranged in irregular verticils and ulti¬ 
mately develop into branching tubes, but in the example under consideration they have 
not reached this stage of growth, displaying as yet little more than sharp projecting 
points. One or two of the spines, b", exhibit a disposition to branch at their free 
extremities ; the more faintly shaded ones represent some seen out of focus. The 
plastic investment is seen at e, not only surrounding the central sphere but extending 
to the extremities of the spines. 
In fig. 42 the densely clustered spines are imperfectly preserved. The outer capsule- 
wall, a, now appears as an extremely thin tissue. At f we find it separating from a 
second thin, structureless layer of membrane, whilst at f we have another spherical 
membrane enclosing a mass of detached cells, g, the diameters of which range from '0008 
to '00125. Most of these cells display their outer cell-walls, with the contracted 
primordial utricle (?) free in the interior of each cell. Fig. 45 represents a transverse 
section of an example in which the spines, b, have become more rigid, and, in addition, 
* The “ spongy substance ” of Mr. Carruthers, 
