OF THE SIBOGA-EXPEDITION, 149 
Thaumatometra thysbe, sp. nov, 
This new form is nearest to 7. alternata as represented 
by the specimens dredged by the »Challenger” at Station 
N°. 170A (cf. »Challenger” Report, Comatulae, pl. 18, fig. 1); 
but P, is much longer with much more elongated seg- 
ments distally, the cirri have much more expanded ends 
to the proximal segments, and the division series are much 
narrower so that there are large spaces between the [Br 
series. 
The centrodorsal is small, rounded conical. 
The cirri are about XL, 15—16, 9 mm. long; the first 
segment is short, the second is about as long as the ex- 
panded distal end, the third is twice as long as the ex- 
panded distal end, and the fourth is slightly longer; the 
following very slowly decrease in length so that the last 
two before the penultimate are from one third to one half 
again as long as broad; the earlier segments have the ends 
greatly expanded, especially the distal end which strongly 
overlaps the bases of the succeeding segments; as the 
segments become shorter the dorsal and ventral profiles 
become straighter and there is a slight lateral compression 
so that they appear wider in lateral view; there is also 
a slight prominence of the median portion of the distal 
dorsal edge. 
The radials are just visible beyond the edge of the 
centrodorsal, but extend well up in the angles of the 
calyx where they diverge slightly distally so that the bases 
of the IBr, are not quite in apposition; the IBr, are very 
short, almost oblong, about four times as broad as long 
exteriorly, slightly shorter in the median line than laterally ; 
the lateral edges of adjacent IBr, make an angle of about 
90° with each other; the distal edges are narrowly everted 
and very finely spinous; the axillaries are about as broad 
as long, the distal edges making approximately a right 
angle with each other; the distal angle is not produced; 
there is a broad rounded posterior angle incising the IBr, ; 
Notes from the Leyden Museum, Vol. XXXIV. 
