366 
Proceedings of the Royal Society 
long-jointed cirri, which vary considerably in appearance. One of 
the largest reaches 36 mm., and consists of forty smooth joints, of 
which all hut the basal and terminal ones are longer than broad, the 
fifth to the tenth being especially so. The cirri attached round the 
upper edge of the centrodorsal are all of this smooth type, and may 
be observed in every stage of growth. But those attached nearer 
the dorsal pole are somewhat different in appearance. They are 
more slender, and their component joints are relatively shorter than 
in the other type ; while the joints have slightly expanded distal 
ends, so as to overlap their successors. This is especially marked 
on the dorsal side, which is produced into a sharp forward project- 
ing spine. I have reason to believe that these characters gradually 
disappear as the joints increase in age, and that the mature cirri of 
the two types are not very different in appearance, especially about 
what might be called the equator of the centrodorsal. But the 
smooth young cirri all round its edge are totally different from the 
spiny ones nearer the dorsal pole. 
Traces of the first radials may be seen at the angles of the calyx ; 
but there is no constancy about their appearance even in individual 
specimens. The second radials are short, even at the sides, and are 
often not visible at all in the middle line of the ray, owing to their 
being very deeply incised to receive the strong backward projections 
of the axillaries. These are quadrate in form, with their sides 
curved, especially the anterior pair ; and they are distinctly longer 
than wide, sometimes almost seeming to overlap the centrodorsal ; 
but much less than half the length is in front of the line joining 
their lateral angles. The first brachials have long outer sides and 
very short inner ones, but (like the second radials) are almost 
invisible in the middle line of the arm, owing to the very strong 
backward projections of the irregularly triangular second brachials, 
which nearly reach the axillaries. Both on these joints and on the 
rudely oblong third brachials, which are much wider than long, the 
pinnule-socket is placed much nearer the dorsal surface than usual. 
The next following joints are short and quadrate, with curved 
proximal and distal edges ; and the pinnule is on the shorter side, 
the longer being marked by a backward projection. 
There are syzygies in the 3rd and 8th brachials, and then at 
intervals of three or four joints throughout the rest of the arm. The 
