422 BULLETIN 8 2, UNITED STATES NATIONAL MUSEUM 



have a strong ventral overlap, and the middle of the distal ventral border is strongly- 

 produced in the form of a sharp and prominent spine this condition reaching a maxi- 

 mum on the eighth or ninth segment, then gradually decreasing in intensity and dis- 

 appearing after about the sixteenth. At about the twenty-fifth segment a slight 

 prominence of the distal dorsal edge is noticeable. After the thirty-sixth the median 

 part of the dorsal edge is produced into a small sharp spine that projects distally in 

 line with the rest of the dorsal surface of the segment. After about the fiftieth 

 segment this spine begins to broaden basally, soon transforming into a high curved 

 spine arising from the entire dorsal surface of the segments, just like the dorsal spines 

 in the distal part of the cirri of Ptilometra macronema. The terminal four segments 

 decrease rapidly in size. The opposing spine is very small, though of normal pro- 

 portions when compared to the very small penxdtimate segment that bears it. The 

 terminal claw is minute. 



The ends of the basal rays are visible as dorsoventrally elongated tubercles m 

 the angles of the calyx. 



The radials are rather prominent, about four times as broad as long, with a 

 rather low rounded tubercle in the median part of the proximal border. The IBr, are 

 oblong, about tkree times as broad as long, in close lateral apposition and somewhat 

 flattened laterally. The IBr2 (axUlaries) are rhombic, about twice as broad as long, 

 with a tendency to rise into a low rounded tubercle at the articulation with the IBrj. 

 The IIBr and IIIBr series are 2, the latter developed exteriorly in 2, 1, 1,2 order. 

 The division series and fii'st four or five brachials are sharply flattened laterally, but 

 owing to the thinness of the ossicles dorsoventrally the flattened lateral border is 

 comparatively narrow. 



The 24-30 arms are 70 mm. long. The first eight brachials are discoidal or 

 oblong, about twice as broad as long, the following gradually becoming more and 

 more wedge-shaped and after the twelfth obliquely wedge-shaped, not quite so long 

 as broad, and in the distal portion of the arms less obliquely wedge-shaped again, but 

 not increasmg in length. The arm ends abruptly with a few mmute incurved segments 

 as in Ptilometra macronema, the termmal phinules exceeding the arm tip by about 4 

 mm. The arms in the proximal half are dorsally rounded and comparatively broad, 

 becoming gradually strongly compressed and carinate distally, the brachials at the 

 same time developing prominent overlapping spines as in Ptilometra macronema. 



Syzygies occur between brachials 3 + 4, again from between brachials 13 + 14 to 

 between brachials 19 + 20 (most commonly between brachials 17 + 18 with rarely an 

 additional syzygy between brachials 7 + 8), and distally at intervals of from 6 to 12 

 (usually 7 or 8) muscular articulations. In one case the first syzygy is between 

 brachials 6 + 7. 



Pi small and weak, about 6.5 raai. long with 10 to 12 segments of which the fii'st 

 is short, the second is rather longer than its distal width, decreasing in width distally, 

 and the remainder are about two and a half times as long as broad. P2 is about 9 mm. 

 long, stiff and spinelike, with 15 segments of which the first is short, the second is 

 rather longer than its distal width, the third is not quite so long as broad, and those 

 following are about twice as long as broad. The pimiule is sharply triangular and the 

 dorsal ridge on each segment is produced distaUy over the bases of the segments 

 succeeding in the form of a slender spine. The third and following pinnules are 



