686 
DR W. T. GORDON ON CAMBRIAN ORGANIC REMAINS 
(figs. 8 and 9, a). The number of rays present in any example is small, but the 
angle of divergence between them is such that the -complete spicule was probably 
heteractinellid. They are siiiiilar in size and appearance to those recorded by 
Taylor from South Australia and from the moraines of the Beardmore Glacier. 
Another multi-rayed example is seen in PI. I, fig. 6, and again the complete 
form is rather difficult to determine. It had certainly not fewer than six rays, 
but it could not be a hexactinellid spicule, since the angle of divergence of the rays 
cannot be reconciled with any possible section of a true hexactinellid. It might 
be said that a section through the centre of a hexactinellid type would approximate 
to the figure, but, as at least two examples have been observed both almost exactly 
alike, the chances are that they are sections of another type of heteractinellid 
spicule rather smaller than the type of figs. 8 and 9. 
We pass now to consider forms of spicule which may be classified with greater 
ease than the above. The first of these is undoubtedly tetractinellid (PI. I, figs. 
7 and 11). In fig. 7 the plane of section is oblique, but all four rays are indicated, 
though only one is complete. The “calthrop” form, however, is very evident. 
The second figure (fig. 11) presents a much more perfect example, since the plane 
of section has cut through almost perpendicular to one of the rays, and the other 
three diverge at the normal angle in calthrop spicules. The vertical ray is 
indicated at a, where a distinct convexity appears in the angle between the 
two rays. 
Examples of hexactinellid spicules also occur, and two of these are figured 
(PI. I, figs. 10 and 14). The great characteristic of such forms is that the rays 
are set with respect to each other at angles which are multiples of 90°. Lastly, 
several very characteristic specimens like those shown in PI. I, figs. 12 and 13, recall 
a similar example figured by Taylor from the Beardmore Glacier locality. His 
specimen certainly bears some resemblance to the spicule of the recent Lelapia, 
but it is really not such a simple form. An examination of his figure * proves that 
at the base of the fork an upward projection appears, and indeed that a perfectly 
horizontal section through it would have looked more like that shown at a of 
PI. I, fig. 12. This fortunate section is exactly in the plane of the spicule, and 
several other specimens occur in the same section. A rather poor example is seen 
at b of the same figure (PI. I, fig. 12), where only the forked ray is visible. Another 
example is figured in the same plate at fig. 13, but again the plane of section has 
passed obliquely across the spicule. The two rays passing to the right and left 
of the forked one at once dissipate the resemblance to Lelapia, but the fact that 
the rays are always at right angles to one another would tend to place this form 
among the hexactinellids. Further, it is quite probable that rays occurred above 
and below, i.e. running perpendicular to the plane of section, in which case we 
may relegate the spicule to a hexactinellid type where one of the rays has become 
* British Antarctic Expedition, 1 907-9. pi. Ixxix, fig. 5. 
