420 BTJLLETIN 82, UNITED STATES NATIONAL MUSEUM 



free laterally. The rays divide four or five times. The IIBr series are 4 (3 + 4). 

 The succeeding division series are 2 (1+2); the first element is only partially united 

 laterally with its fellow. 



The 56 arms are about 90 mm. long. The first 2 brachials form a syzygial pair 

 which is oblong or nearly square. The next 2 brachials are usually articulated, but 

 may form a syzygial pair. The following 2 or 3 brachials are transversely oblong, 

 and their immediate successors are longer, wedge-shaped, with slightly overlapping 

 distal ends. After this both length and breadth diminish and the brachials become 

 blunter and smoother, elongating again toward the arm tips. The arms are dimorphic, 

 those on one side of the calyx (probably the posterior) being shorter with only 60-70 

 brachials and tapering more rapidly than the longer anterior arms with 80-90 

 brachials. 



The first syzj'^gy is between brachials 1+2, and there is frequently another 

 between brachials 3+4, especially on those undivided arms borne by axillaries 

 which carry division series on their other faces. The next syzygy is usually between 

 brachials 9 + 10 or 10+11, and the distal intersyzygial interval is 3, or sometimes 

 only 2, muscular articulations. 



Pd is moderately long, with a well-marked tenninal comb. The next pinnule 

 normally is Pi. The size of this pinnule and also of P^ varies very considerably, 

 being greater on the outer than on the inner arms of each ray. There is a gradual 

 decrease in size from the first pinnule to those on the fourth and fifth brachials 

 beyond, after which they increase again, losing the terminal comb at about the 

 eighth brachial. Their squarish segments have spiny tufts in the mediodorsal line, 

 and at the distal end of each there are one or two rather larger lateral spines. Toward 

 the arm tips the pinnules gradually become more slender, but increase very little in 

 length; their segments become oblong, and the large lateral spines are almost entirely 

 limited to their outer sides. 



The disk is missing. Some of the shorter arms have only an imperfect groove 

 and tentacular apparatus, or none at all. 



The diameter of the radial ring is 10.5 mm. 



The skeleton is grayish white, the perisome a darker gray. 



Herklots published a colored plate showing this specimen as it appeared in life. 

 The calyx and division series are orange brown, the undivided arms lighter and rose 

 pink, becoming bright yellow at the extreme tip. The figure gives 40 arms, and 

 shows that the disk was lacking at the time it was drawn. Herklots remarked that 

 Muller in his original description said that the color, as preserved in alcohol, was 

 brown. 



In the specimen from north of Port Walcott, Western Australia, there are 5 or 

 6 successive axillaries on each postradial series, the arms being in the vicinity of 

 100 in number, and probably about 70 mm. in length. All the IIBr series are 4 

 (3 + 4), and all the following division series, with but two or three exceptions, are 2 

 (1+2), the exceptions being 4 (3 + 4). The IBri are laterally united, but the IBr 

 axillaries are widely separated. The brachials have slightly prominent and finely 

 spinous distal ends. 



