476 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



11 + 12 to between brachials 14 + 15. The distal intersyzygial interval is from 2 to 

 7, but usually 4, muscular articulations. 



P D may reach 25 mm. in length, but is usually between 15 and 20 mm. The 

 next, whether on the IIIBr or IVBr series, is slightly shorter. The following pinnule 

 is only half as long, and PI is always much shorter than those preceding. P 2 and P t 

 are the shortest pair. The distal pinnules reach about 8 mm., and become much 

 shorter toward the tip of the posterior arms. The comb on the proximal pinnules is 

 sometimes only represented by a trace. It occurs as far as the pinnule of the tenth 

 brachial. 



The disk is 35 mm. in diameter, either naked or somewhat plated. The mouth 

 is interradial. 



The color in alcohol is light yellowish green, grayish brown, or dark brown. 



The expanse is 300 mm. This would mean an arm length of 1 50 mm. 



Hartlaub remarked that it is only rarely that all of the rays in any given specimen 

 show the typical arrangement of the IIIBr series 2 externally and 4 (3+4) internally. 

 This occurred in only 3 out of his 17 specimens. Usually on 1 or 2 rays the IIIBr 2 

 and IIIBr 4 (3 + 4) series are irregularly arranged, and in 1 specimen only a single 

 ray shows the typical arrangement. But rays on which the 4 IIIBr series have the 

 same number of elements are very rare. It is noteworthy that in specimens with an 

 irregular arrangement of the IIIBr series the IIBr series are also irregular, being 2 

 instead of 4 (3 + 4). Hartlaub says that such abnormal IIBr series are always fol- 

 lowed by an abnormal arrangement of the succeeding IIIBr series. 



I have examined 2 of Doctor Hartlaub 's specimens, 1 in the Berlin and 1 in the 

 Leyden Museum, but have nothing to add to his account. 



According to Reichensperger, the specimen collected by Professor Strubell at 

 Amboina is a robust example with 145 arms which are up to 145 mm. in length. The 

 centrodorsal is a rather thin pentagonal disk slightly sunken in the center. The cirri 

 are III, 14-15, 13 mm. long; there are traces of a few more rudimentary cirri. All of 

 the IIBr series are 4 (3 + 4). The IIIBr series for the most part are 4 (3 + 4). The 

 disk is 35 mm. in diameter. The mouth is interradial. P D is up to 25 mm. long. The 

 combs are poorly developed. The color in alcohol is red brown. 



Professor Doderlein's specimen from Amboina has the cirri XIV, 15-16. A few 

 of the IIBr and IIIBr series are 2 instead of 4 (3 + 4). The color is dark violet with 

 the outer half of the arms whitish. 



The magnificent specimen from Siboga station 164 has about 100 arms which are 

 about 150 mm. long. The division series are broad, interiorly united and closely 

 flattened against each other. The division series on adjacent rays are closely flattened 

 against each other as far as the IIBr 2 , or even the IIBr axillary, beyond which point 

 the perisome is solidly plated. On 3 of the rays the IIIBr series show the normal 

 arrangement, being 2 4 (3 + 4) 4 (3 + 4) 2. On one ray the IIIBr series are 

 24 (3 + 4) 4 (3 + 4) 4 (3+4), and on the fifth they are 2 2 4 (3 + 4) 4 (3+4). 

 The centrodorsal is very small, concave dorsally, and sunken within the radial ring. 



The specimen from the Aru Islands as described by Reichensperger is unusually 

 stout, with 151 arms which are up to 140 mm. long. With the exception of the outer 

 IIIBr series on 3 rays, which are 2, all the division series are 4 (3 + 4). The centro- 



