350 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



about 3 times as broad as long and bear a cylindrical, blunt, spinelike tubercle, some- 

 times a pair, on the proximal margin, and another on the distal margin in the median 

 line. The IBr2 (axQlaries) are about 3 times as broad as long with a low obtuse distal 

 angle. On each of the distal sides there are from 1 to 3 projections somewhat similar 

 to those on the IBr, but flattened. The IIBr series are 4(3+4), in one case 3(2+3). 

 On the first 3 segments the spinelike tubercle in the middle of the distal margin is 

 prominent, while the axillary may have a somewhat smaller one on either side. An 

 additional similar tubercle may be developed in connection with the well marked 

 anterolateral angles. 



The arms (number not given) are about 75 mm. in length. The earlier brachials 

 are quadrilateral, with conspicuous anterolateral angles on the side bearing the pinnule. 

 The median spinelike tubercle is also often developed. After the seventh or eighth 

 the brachials tend to become triangular and the distal margins tend to flare, but there 

 is no overlapping. 



Syzygies occiu- between brachials 2+3 on arms following IIBr series, and between 

 brachials 3+4 on arms arising directly from the IBr axillaries. The second syzygy 

 is somewhere between the eighth and foiu-teenth brachials. The distal intersyzygial 

 interval is 6 or 7 muscular articulations. 



Pi is about 7 mm. long, somewhat prismatic, curved inward, flexible, though not 

 at aU flagellate, and rather stout throughout. It is composed of about 15 segments 

 of which the first is notably enlarged, but not the second. P2 is erect and spine- 

 like, not at all prismatic, about 13 mm. long, composed of 15 nearly cylindrical seg- 

 ments with spiny distal ends all but the terminal and two basal longer than broad. 

 P3 is very similar, perhaps a little longer. P4 is similar, perhaps a little shorter than 

 P3. Ps to Pio are similar but successively shorter and with fewer segments which 

 have less and less spiny distal margins. Pu is about 8 mm. long and is composed of 

 11 segments. The succeedmg pinnules are distinctly prismatic and gradually in- 

 crease to about 10 mm. in length. The side- and covering-plates are well developed. 



The color of the single dry specimen is purple and white. The centrodorsal, 

 the dorsal surface of the arms and pinnules, and scattered spots elsewhere are white 

 or whitish. The IBr series are dirty whitish with a purple tinge. The IIBr series, 

 a few of the lowest brachials, a conspicuous line along each side of each arm, and the 

 oral surface of the pinnules, at least on the basal portion, are more or less deep purple. 



Localities. — Thirteen miles north by west of Double Island Point, Queensland; 

 46-47 meters; Australian Federal Fisheries Investigation Ship Endeavour [H. L. 

 Clark, 1916] (1, Australian M us.). 



No locality [A. H. Clark, 1912, 1913] (1, B. M.). 



Remarks. — From the fact that the type specimen of Oreometra mariae in the 

 British Museum was designated Antedon macronema I suspected that it had come 

 from eastern Australia. Its general appearance is sufiiciently like that of Ptilometra 

 australis to mislead anyone casually going over a collection of Australian echinoderms 

 into referring it to that species ; but had it been sent from any other region it certainly 

 never would have been referred to this distinctively Australian form. 



I carmot see any reason for supposing that Oreometra pericalles is specifically 

 different from R. mariae. Dr. H. L. Clark says that the differences in the IBr series 

 and in the pinnules forbid referring the type of pericalles to mariae. But the differ- 



