280 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



bluntly wedge-shaped. The first syzygial pah- (composed of brachials 3+4), and the 

 four next brachials are short and oblong. The following brachials are short, bluntly 

 wedge-shaped, and overlap rather strongly so as to give the arms a serrate appear- 

 ance; the brachials become more oblong again at about the middle of the arm. 



Syzygies occur between brachials 3+4, again from between brachials 20+21 to 

 between brachials 26+27, and distally at intervals of 8-13 (usually 10 or 11) muscu- 

 lar articulations. 



The size of the lower pinnules varies considerably according as they are on the 

 outer or inner arms of the postradial series. P D is moderately long and stout at the 

 base but tapers rather rapidly. P, on the outer arms is both longer and stouter 

 than PD, sometimes very much so, while P 2 is equal to, or slightly longer than, P,. 

 P a and P b are both smaller tha'n the corresponding pinnules on the outside of the arm, 

 and the size decreases to P 4 and P d , after which it gradually increases again. On the 

 inner arms of the postradial series the fifth brachial usually bears the largest pinnule, 

 those on the second and seventh brachials being about equal. The distal ends of the 

 cylindrical segments of the large proximal pinnules are raised into slight spines. 



The disk is naked and considerably incised; it is 10 mm. in diameter. Sacculi 

 are closely set along the pinnule ambulacra. 



The color is purple with whitish bands. 



Notes. My notes on Carpenter's type specimen, which I examined at the 

 Hamburg Museum in 1910, are as follows: The centrodorsal is moderate in size with a 

 slightly convex dorsal pole 2 mm. in diameter. The cirri are about XX, 28-33, from 

 17 to 20 mm. in length. The longer proximal segments are about as long as the distal 

 width, sometimes very slightly longer. The outer segments are about one-third again 

 as broad as long. The earlier segments have slightly thickened and prominent distal 

 dorsal edges. The ninth-twelfth (usually the latter) and following develop long and 

 sharp dorsal spines. Of the 10 IIBr series 7 are 4(3+4) and 3 are 2. There are 

 present 3 IIIBr 2 series, all internally developed. The 23 arms were probably about 

 50 mm. long. The longest pinnules have about 22 segments. The distal edges of 

 the third and following segments of the proximal pinnules are strongly everted and 

 very finely spinous instead of being with broad lateral processes as in H. crenulata. 

 The disk is completely covered with a pavement of small irregular plates. 



The type specimen of Antedon brockii from Amboina was described by Hartlaub 

 in the following terms: The centrodorsal is rather large and thick with a bare flat 

 dorsal pole. The cirri are arranged in two and a partial third marginal rows. Cirri 

 about XXX, 30-37, reaching 30 mm. in length, stout, and not entirely confined to 

 the border of the centrodorsal. Some of the cirrus segments may be a little longer 

 than broad. Strong dorsal spines are developed from the tenth or twelfth segments 

 onward. The radials are only very slightly visible. The IBr! are short, partially 

 united laterally. The IBr 2 (axillaries) are short and pentagonal. The IIBr series 

 are 4(3+4). The IIIBr series are 2, developed only internally. Feeble synarthrial 

 tubercles are developed, the best developed being between the first two brachials. 

 The 28 arms are about 140 mm. long and composed of short brachials of which the 

 first 9 or 10 have smooth articulations and are longer than those following. The first 

 syzygial pair (composed of brachials 3+4) is about as long as broad. The few 

 immediately following are discoidal and form with each other feeble alternating eleva- 



