148 RECENT UNSTALKED CRINOIDS 
Thaumatometra alcyon, sp. nov. 
The long cirri of this species which have short distal 
segments resemble those of the species of Trichometra, but 
the short P, and the gonad on P, place it in Zhauma- 
tometra; it appears to be most closely related to Th, laevis. 
The centrodorsal is rounded conical. 
The cirri are L—LX, 27—28, 18 mm. long; the longest 
segments are about three times as long as their median 
diameter, or about twice as long as the somewhat expanded 
distal ends; the last six or seven are slightly longer than 
broad, 
The radials are just visible beyond the edge of the 
centrodorsal; their distal angles are slightly separated; the 
IBr, are extremely short; the axillaries are broader than 
long, with all the sides concave ; the lateral angles extend 
well beyond the distal angles of the IBr,, and there is 
a prominent posterior process incising the IBr,; the arms 
are probably about 60 mm. long; the first brachial is very 
short, basally not quite in apposition, the interior edges 
diverging nearly in a straight line; the following brachials 
resemble those of the other species of the genus; they have 
slightly overlapping and finely spinous distal ends, 
P, is 7 mm. to 9 mm. long with from nineteen to twenty- 
three segments, weak and slender; the first four segments 
are about as long as broad and the following slowly increase 
in length so that the outer are twice as long as broad or 
slightly longer, with somewhat expanded and spinous distal 
ends, and the terminal are much elongated; P, is about 
10 mm. long with sixteen segments of which the first two 
are about as long as broad, the third and fourth twice as 
long as the median diameter, and the following greatly 
elongated; it is considerably stouter than P, and bears 
a gonad on the fifth-eighth segments; the distal pinnules 
are 10 mm. long with about fifteen segments which have 
much expanded overlapping finely spinous distal ends. 
Type locality. — »Siboga” Station N°. 251. 
Notes from the Leyden Museum, Vol. XXXIV. 
