462 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



one-third, or rather less, broader than long and bear subterminal tubercles which in 

 the last 3 are moderately sharp. 



The adult specimen from Port Hedland has about 150 arms which are about 

 100 mm. long. Three of the IIBr series are 2 and 7 are 4 (3 + 4). On all 3 of the IIBr 

 2 series the normal order of the IIIBr series is reversed, these being 4 (3 +4) externally 

 and 2 internally. On one of the other IIBr series there are 2 IIIBr 4 (3 + 4) series. 

 About half a dozen of the outer division series are 4 (3 + 4) instead of the usual 2. All 

 the other division series are regular. The centrodorsal is only slightly raised above 

 the dorsal surface of the radial pentagon. It is irregularly pentagonal in shape, with 

 partially obliterated cirrus sockets about the periphery. One fully developed cirrus 

 11.5 mm. in length with 16 segments remains, and there are 2 rudimentary cirri. 

 The dorsal portion of the perisome between the division series is heavily plated. The 

 color is dull yellowish white, with the dorsal perisomic areas and the extreme borders 

 of the division series yellow brown. The sides of the undivided arms are usually 

 darker than the dorsal surface, sometimes a deep yellow brown. Some of the free 

 arms have a more or less perfectly developed dark brown mediodorsal stripe. 



One of the three young specimens from Port Hedland has 67 arms 65 mm. long. 

 The centrodorsal is thin discoidal, small, the bare dorsal pole being 2 mm. in diameter. 

 The cirri are XX, 14-16, 9 mm. long. The first cirrus segment is short, the fourth 

 is about as long as broad, the sixth or seventh is the longest, from one-third to one- 

 half again as long as broad, and the last 6 or 7 are about as long as broad. The 

 outermost 7 or 8 bear blunt spines or tubercles on the distal dorsal border. The 

 longer earlier segments are slightly constricted centrally, but this feature is scarcely 

 noticeable. The color is grayish white, with a median stripe of darker on the arms. 

 The interradial perisome is heavily plated. 



A second specimen has 59 arms 60 mm. long. The cirri are VII (plus 9 unde- 

 veloped), 15, 10 mm. long. The dorsal perisome is completely plated, but the 

 plates are small. The color is yellow brown, with traces of a broad mediodorsal 

 band of darker. 



The third specimen is similar, but smaller. 



These 3 specimens differ considerably in the number of arms, and in each there 

 is large variation in the number of arms on the different rays. Regenerating division 

 series and arms are frequent in all of them. 



One of the 2 specimens from Broome has 73 arms 135 mm. long. The cirri are 

 XVII, 11 mm. long. There are a few small scattered nodules on the disk. The 

 color is grayish brown. 



The other specimen from Broome has 68 arms 125 mm. long. The cirri are 

 XIV. The disk is thickly studded with small calcareous nodules. The color is 

 bright yellow green, with the centrodorsal and cirri light slaty. 



In the specimen from Western Australia the cirri are XII, 17-18, 13 mm. long. 

 There are slight dorsal tubercles on the last 6 segments. The carination of the 

 earlier pinnule segments is very prominent. 



The specimen from northwestern Australia has VII cirri. 



In the arm fragments from Mermaid the extravagant dorsal processes on the 

 third-fifth, and to a lesser degree the sixth, pinnule segments prove conclusively 



