PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 523 



The second brachials arc irregularly quadrate, the two on each post-radial series being 

 in contact interiorly so that a prominent rhombic gap is left between the first brachials. 

 The first syzygial pair (formed of the third and fourth brachials) is slightly longer 

 interiorl}'- than exteriorly, and about as broad as the interior length. The next four 

 brachials are slightlj' wedge-shaped, twice as broad as the median length. The follow- 

 ing brachials become more obliquely wedge-shaped. [Note by A.M.C: The width 

 at the firet syzj-gj' is 1.5 mm. and the length from IBrj to the second syzygy (9-FlO) is 

 10.0 mm.] 



In Ps. vnreni the 10 arms are probably about 60 mm. long. The first brachials are 

 2 or 3 times as long exteriorly as interiorly, basally in contact interiorly. The second 

 brachials are very much shorter interiorly than exteriorly. There is a slight synarthrial 

 tubercle on the line of union between the first and second brachials. After the twelfth 

 the ends of the brachials become oblique. The first 10 brachials have their distal edges 

 somewhat thickened and everted; distally the arms are smooth. 



The distance from the radials to the first syzygy is 3.2 mm. 



In Ps. inusitxita syzygies occur between brachials 3+4, 9 + 10, and 14+15, and 

 distally at intervals of usually 4 muscular articulations; but the distal intersyzygial 

 interval can only be estimated, as the outer part of the arms in all the specimens is lost. 

 [Note by A.M.C: In a specimen from Siboga station 45 the second syzygy is very 

 irregular in position; on the six remaining arms it occurs twice each at brachials 11 + 12, 

 10+11, and 9+10. The length from the IBti to the second syzygy at 9 + 10 is 13.5 

 mm. and the width at the first syzygy is 2.0 mm. The centrodorsal I estimate as 



4.5 mm. in basal diameter.] 



In Ps. wireni, according to Gislen, syzygies occur between brachials 3+4, 9 + 10, 

 14 + 15, and 21+22; or between brachials 3+4, 9 + 10, 16 + 17, 20+21, etc., with 

 a distal intersyzygial interval of 3 muscular articulations. 



In Ps. wireni P, is 6 mm. long, very slender and flagellate, composed of about 30 

 segments, of which the first 5 are broader than long to as long as broad with their angles 

 cut away, and the following are slender, from half again to twice as long as broad, and 

 more or less constricted centrally. Pa is similar, \vith about 25 segments. P2 is stouter 

 than Pi, from 3.5 to 4.0 mm. long, with 11 to 12 segments, of which the first 3 are broader 

 than long and the remainder arc from two to two and a half times as long as broad; the 

 fifth to eighth segments bear a large gonad. P,, is similar, with 11 segments. The 

 distal pinnules are 5.5 mm. long, with 16 segments, of which the first and second are 

 short and the third and following are from two and a half to three times as long as 

 broad, slender, with somewhat swoUcn articulations. 



In Ps. inusitata Pi is exceedingly slender and delicate with the first segment broader 

 than long, the next 5 about as long as broad, the seventh slightly longer than broad, and 

 the following becoming greatly elongated. P2 is much stouter with the first 4 segments 

 short but the following rapidly increasing in length and the outer exceedingly elongated. 



In Ps. wireni the disk is slightly incised, without visible calcareous deposits, and 

 measures 4.5 mm. in diameter. 



Of the specimens taken by Dr. Th. Mortensen in Japan, one has the centrodorsal 



1.6 mm. in diameter and 1.0 mm. in height. The cirri are in five groups separated by 

 interradial cirrus-free areas, in each group two rows converging towards the tip of the 

 centrodorsal. The cirri are in three to four whorls and there are sL\ to seven in each 

 group. One cirrus is preserved to the fifteenth segment. The sixth to eighth segments 



