OF THE SIBOGA-EXPEDITION, KDL 
brachials resemble those of Atelecrinus except in being 
more rugged. 
All the pinnules are present, and resemble those of the 
large species of Zenometra or of Psathyrometra. 
Atopocrinus sibogae, sp. nov. 
The centrodorsal is as described in the generic diagnosis; 
deep subradial clefts separate the centrodorsal from the 
radials; high and narrow basal rays of which the outer 
ends are broadly pentagonal and convex cap the ends of 
the interradial ridges of the centrodorsal though entirely 
separated from it by very thin lines which represent the 
edges of the greatly reduced basals; the general aspect of 
the centrodorsal and the proximal structure is very like 
that of the large species of Zenometra or of Psathyrometra. 
The cirri are lacking. 
The radials are much shorter than those of Atelecrinus 
and much more recumbent. 
There are five arms, very stout and probably also very 
long; the distance from the subradial cleft to the distal 
border of the tenth brachial is 19 mm.; there are no IBr 
series; the brachials, though much more rugged, are similar 
to the brachials of the species of Atelecrinus and therefore 
differ from those of the other comatulid genera in passing 
at once into the triangular form without the intervention 
of more or less oblong brachials; the first syzygy normally 
occurs between the fourth and fifth brachials instead of 
between the third and fourth, this species agreeing with 
the species of the PENTAMETROCRINIDAE in this respect as 
well as in the absence of the IBr series. 
The lower pinnules are all present (though all are absent 
in the species of Atelecrinus), and resemble those of the 
larger species of Zenometra or Psathyrometra; P, is about 
16 mm. long; P, is 15 mm. long and is composed of 
ten segments. 
The disk resembles that of Atelecrinus balanoides and is 
INotes from the Leyden Museum, Vol. XXXIV. 
