421 
distribution and on other problems connected with these animals. As 
it will take some time to digest the data presented and to prepare the 
final comprehensive report for the »Siboga« series it has seemed advis- 
able to publish preliminary descriptions of the new forms in order to 
guard against anticipation. 
In the present paper those belonging to the families Calometridae 
_ and Thalassometridae are considered. 
Family Calometridae. 
Neometra sibogae sp. nov. 
The centrodorsal is thin discoidal, the broad polar area flat, 4 mm 
in diameter; the cirrus sockets are arranged in a single, fairly regular, 
marginal row. 
The cirri are XV, 31-36, about 25 mm long, large and stout; their 
bases are crowded against those of the adjacent cirri, and the first seg- 
ment is more or less sharply flattened laterally; the first two segments 
are about twice as broad as long, the following gradually increasing in 
length and becoming nearly, sometimes quite, as long as broad on the 
fifth; the next two or three segments are similar, and the following very 
gradually decrease in length so that those in the outer fourth of the cirri 
are abouttwice as broad aslong; in the outer fourth or fifth the cirri taper 
very gradually so that the tip is comparatively slender; the distal edges 
of the segments all around is everted and prominently overlapping; from 
the tenth onward the dorsal surface of the segments is sharply carinate; 
at first this affects only the distal part, but it soon comes to occupy the 
entire dorsal surface of the segments, standing up in the form of a high 
median keel the crest of which is parallel to the longitudinal axis of the 
cirrus. . 
The radials are even with the edge of the centrodorsal in the median 
line, but are strongly produced in the angles of the calyx where they 
separate widely the bases of the IBr;; the ventral edge of this anterior 
process, which is straight and not spatulate or otherwise modified, is 
equal in length to the lateral edges of the IBr, ; the cirrus sockets en- 
croach more or less upon the radial as do those of Oreometra mariae. 
The division series spread out horizontally from the radials as in 
the species of the genus Comanthus; the division series are very narrow 
and very strongly rounded, so that they are very widely separated; the 
extreme ventrolateral border of the ossicles of the division series is pro- 
duced in the shape of a thin flange with a smooth and sharp outer border 
which runs from the distal edge of the interradial production of the 
radials to the second brachial; but the produced borders are dorsally 
only visible as far as the IBr axillary; from the ends of the interradial 
