238 
of the IBfj, are bordered with exceedingly fine spines. The synarthrial tubercles, though broadly 
rounded, are rather prominent. 
The first brachial is short, three times as long exteriorly as interiorly, slightly longer in 
the median line than interiorly ; the interior edges are in apposition ; the exterior edges are 
slightly concave: the distal inner corners bear a rudimentary tubercle similar to that on the 
outer part of the lateral borders of the IBr,. These tubercles on the IBr,, with the adjacent 
tubercles under the lateral angles of the axillaries, almost completely close what otherwise 
would be a large rhombic water pore. 
The second brachial is much larger than the first, in direct dorsal view almost an 
equilateral triangle; the outer border is slightly concave; the distal edge is very finely spinous. 
The first syzygial pair (composed of the third and fourth brachials) is slightly longer 
interiorly than exteriorly, about twice as broad as long in the median line, the sides slightly 
concave, the distal edge very finely spinous. The following brachials rapidly become obliquely 
wedge-shaped, after the second syzygy triangular and as long as broad with very finely spinous 
edges, and later obliquely wedge-shaped again. 
Syzygies occur between the third and fourth, ninth and tenth and fourteenth and fifteenth 
brachials, and distally at intervals of four (more rarely three) oblique muscular articulations. 
The brachials have projecting and overlapping finely spinous distal edges, and the dorsal 
surface is marked with fine parallel longitudinal ridges. The arms are 120 mm. long. 
Pj is from 12 mm. to 13 mm. long, composed of 20 segments of which the first is 
slightly longer than broad, the second is. about half again as long as broad, the third is about 
twice as long as the proximal length, and the fourth and following are about two and one 
half times as long as broad; Pj is the longest pinnule on the arm, though only slightly longer 
than the distal pinnules; it is smooth with long segments, rather stiff and moderately stout, 
tapering moderately in the proximal third, more gradually from that point onward; in its general 
appearance, especially in the very close union of its segments which have perfectly straight 
ends, it recalls Pj in the larger species of Psafkvroinefra. 
Pj is from 10. o mm. to 10.5 mm. long with 17 segments, similar to P^ but tapering 
rather more evenly. 
P„ is 8 mm. long with 13 or 14 segments, similar to Pj and P„, but with the segments 
more enlarged distally and proportionately smaller. 
P^ is 5.5 mm. long with 12 or 13 segments, similar to P3, but with the distal segments 
slightly more elongated. 
P5 is 5.5 mm. long, resembling the preceding pinnule but more .slender, with 12 or 13 
segments of which the distal are more elongated. 
Pg is 7 mm. long with 15 segments, longer, less slender and less stiff than those preceding, 
the distal segments with very slightly spinous edges. The following pinnules are similar to P„. 
The distal pinnules are e.xceedingly slender, i i mm. long with 23 segments of which 
the first two are unusually enlarged and the following are moderately elongate with swollen 
articulations and finely spinous ends. 
The specimen described is that from Stat. 253. 
