199 
2. Mastis^otfieira pacifica nov. sp. 
The centrodorsal is very Hat, almost discoidal, willi a lar^e Hal dorsal ijoie 2 mm. in 
diameter; the cirrus sockets are arran-^ed in two and a partial third alternating marginal rows. 
The cirri are about XXW, 12 — 16 (the longest usually 14 — 16), 12 mm. to 14 mm. 
long, in general appearance strongly suggesting those of Antedon petasus ; the first segment is 
very short, the second about twice as broad as long, the third nearly as long as broad, the 
fourth slightly longer than liroad, the fifth the longest, from one third to one half again as 
long as the median diameter, the following of about the same f)roportions; from the fourth or 
fifth segment onward the cirrus in lateral view increases slowly in diameter so that the outer 
portion, which is rather strongly recurved, is nearly twice as broad as the pro.\imal; the 
opposing spine is minute; the terminal claw is nearly as long as the penultimate seorment, 
stout and strongly curved. The earlier cirrus segments have a slight central constriction; the 
outer in lateral view have a quite straight dorsal, and a nearly straight ventral, profile. 
The distal border of the radials is even with the rim of the centrodorsal. 
The lBr| are very short, from five to six times as broad as long, with the distal and 
pro.\imal edges parallel and the lateral edges slightly convergent, making an angle of about 
90° with those of the adjacent IBr,, the perisomic area thus e.\posed being entirely covered by 
a conspicuous group of perisomic interradials. 
The IBr^ (axillaries) are triangular, half again as broad as long, with the anterior angle 
somewhat produced. 
The brachials resemble those of the other species of the genus; the distal edges are 
slightly produced and finely spinous. 
Syzygies occur between the third and fourth brachials, again between the ninth and tenth 
and fourteenth and fifteenth, and distally at intervals of three oblique muscular articulations. 
The arms are 105 mm. long, becoming extremely slender and attenuate distally. 
P, is 15 mm. long, composed of 30 segments of which the first is broader than long, 
the second half again as long as broad, and the third and following are twice as long as 
broad, becoming longer in the distal half; from about the fifth onward the segments have 
overlapping and prominently spinous distal ends. The pinnule is considerably stouter ba.sally 
than P, and the succeeding pinnules, but becomes exceedingly attenuated and flexible in the 
distal half. 
P., is 10 mm. long with 24 segments, more slender than P, with relatively longer 
segments which have more prominently spinous distal ends. 
P.. is 7 mm. long with 13 — 15 segments, tapering more gradually than P, and hence 
appearing stouter, and without the long flagellate tip. 
P^ apparently resembles P.;, but is somewhat shorter. 
This species is described from two specimens from Tahiti, Society Islands, in the Zoolo- 
gical Museum (Staatssammlung) at Munich; they were part of the lot including the specimens 
upon which Etiantcdoji tahitiensis is based. 
