66 
characteristic of sueh species as Pentametrocrinus varians or P. japonicus. The first cirrus 
segment is very short, the second not so long as broad, the third nearly or quite twice as long 
as the proximal diameter, the fourth and following about four times as long as the median 
diameter; the sixth-eighth segments are the longest, the length from that point onward diminishing 
almost imperceptibly so that the seventeenth and following are slightly over twice as long as 
broad and the penultimate half again as long as- broad, tapering somewhat distally; the opposing 
spine is represented by a small rounded subterminal tubercle; the terminal claw is slightly longer 
than the penultimate segment, very slender, very sharp, and only slightly curved. The second 
and third cirrus segments are rather strongly constricted 
centrally ; the sixth and following have moderately expanded 
and slightly overlapping distal ends, this character gradually 
dying away distally. The cirri are rather strongly com- 
pressed laterally from the fifth segment onward. 
The radials are just visible beyond the edge of the 
centrodorsal ; their distal border is swollen and everted, 
smooth or evenly tuberculated. 
The I Br series (the first two ossicles following the 
radials) forms an oblong unit which is not quite twice as 
broad as long; both the proximal and distal borders are 
turned outward, the former slightly, but the latter standing 
up at right angles to the general surface of the segment, 
, . , . c ■ c r J- ■ ■ with a smooth and somewhat thickened edg-e ; the proximal 
Lateral view of a specimen of huaiocrt/iusjtinceiis ^ ^ ^ 
from Stat. 167. Natur.ii size. (Courtesy of the u. s. border may be more or less scalloped, and it bears just 
National Museum). .... . , 
within it a prominent rounded tubercle ; the produced distal 
edge is thickest and most prominent in the middorsal half, this portion being evenly concave ; 
the remainder of the distal edge may be irregularly scalloped. 
The five arms are 90 mm. long; the first brachial is oblong, two and one half to three 
times as broad as long; the proximal and distal edges are slightly thickened and everted; the 
second brachial is similar, but the distal edge is prominently everted, especially in the middle 
third where it is thickened, and concave distally, and stands up vertically from the dorsal 
surface of the joint face; the third and fourth brachials (forming the first syzygial pair) are 
together slightly longer on one side than on the other, about twice as broad as the lesser 
length, resembling the IBr series but with the tubercle within the median part of the proximal 
border only just indicated; the following three brachials are slightly wedge-shaped, about twice 
as broad as the median length, their distal borders everted as described for the second brachial, 
but progressively less and less so; following brachials triangular, about as long as broad, with 
slightly produced and overlapping distal edges; the fourth-ninth bear a low rounded median 
carination, this after the ninth becoming the low rounded zigzag keel characteristic of the arms 
of all the species of the genus, which is traceable throughout the length of the arm. Syzygies 
occur between brachials 3 -f 4, 8 -|- 9 and 13+14 (usually) to 15 -f i6, and distally at intervals 
of from 2 to 4 (usually 3) oblique muscular articulations. 
