328 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



The larger specimen has 21, the smaller 19, rather slender arms. The first brachials 

 are in close lateral apposition. The lower approximately discoidal brachials as far as 

 about the eleventh in the larger specimen have strongly produced distal ends which are 

 partially beset with smooth sharp spines. On some arms these brachials are markedly 

 saddle-shaped (that is, centrally constricted) and spiny, this feature being much less 

 developed on others. Quite characteristic it is for their surface to have irregular 

 cavities, and as a result a grooved or furrowed appearance. A central small knob may 

 be distinguished on all the brachials except the more saddle-shaped ones with a spiny 

 edge. These small knobs form a continuous row as far as the radials. The distal edges 

 of the brachials often have a spine or process on each side. The proximal brachials of 

 the small specimen are much smoother; only here and there may there be seen a pro- 

 nounced grooving of the surface and a small knob in the middle. The brachials follow- 

 ing are triangular with arched distal ends, and have smooth surfaces. Toward the 

 arm tips they have a tilelike overlap, and the distal edge here is slightly convex. 



In arms arising from a IBraxillary the first syzygy is between brachials 3+4, in arms 

 arising from a IIBr or IIIBr axillary between brachials 1+2, this being often followed 

 by one between brachials 3+4 or between brachials 4 + 5. The next syzygy is usually 

 at about the twenty-first brachial, those following often at intervals of 9 or 10 muscular 

 articulations, and farther out at intervals of about 6 muscular articulations. In the 

 smaller specimen, in arms arising from a IIIBr axillary the syzygies are at shorter 

 intervals, for instance between brachials 1+2, 4 + 5, 17+18, 23+24, 29+30, and 

 34+35; or between brachials 1+2, 6 + 7, 15 + 16, 21+22, and 27+28; an arm arising 

 from a IBr axillary has the first syzygy between brachials 3+4, the next between 

 brachials 6 + 7, and the third between brachials 22+23. 



The lowest pinnule in the larger specimen is on the IIBr 2 if the division series are 

 4(3+4), and there is always a pinnule on the second brachial. Only a PI is preserved 

 entire. It is 12 mm. long with 30 short segments of which the lower are broad and 

 carinate. P 2 is markedly shorter and has only 17 segments. The pinnule following on 

 the same arm is not complete. P 4 is 5 mm. long with about 12 segments. The lower 

 segments of all these pinnules are broadened, but there is no clearly marked carination. 

 On other arms the lower segments of these same pinnules are sharply carinate, which 

 appears to be the general rule. The distal pinnules have usually 13 segments, most of 

 which are elongate and cylindrical. In the younger specimen a carination of the lower 

 pinnules is scarcely present. On the larger it reaches to about the sixteenth brachial. 



The ambulacra of the pinnules are provided with side and covering plates, and with 

 numerous inconspicuous sacculi. The disk is somewhat incised. In the larger speci- 

 men it is scarcely 10 mm. in diameter, in the smaller 6 mm. It is thickly beset with 

 calcareous granules which are rounded or elongate and are mostly not in contact with 

 each other. 



The larger has the arms with an estimated length of 100 mm., the smaller of 

 60 mm. 



In alcohol the skeleton is brownish white, the disk and soft parts of the arms dark 

 brown. 



Hartlaub pointed out that Pourtales' original description gave the number of arms 

 as 20, with a spread of 200 to 230 mm. (or an arm length of 100 to 115 mm.). It differs 

 from his description in stating that the radials are entirely concealed, and that at about 



