320 in I i .1 UN 82, IMTKI) STATES NATIONAL MUSK' U 



The opposing spine is longer than the spines on the preceding segments, sharp, hi- 

 lar in profile, rather deader, with tho apex median; it reaches a length about 

 equal to half the width of the penultimate segment. The terminal claw is longer 

 than the penultimate Begment, slender, more strongly curved proximally than distally. 

 The radialfi are just visible in the midradial lino beyond the rim of the centro- 

 dorsal and form low triangles in the interradial angles of the calyx; their anterolateral 

 corners are slighth swollen. The IBr, are oblong, four times as broad as long, and 

 almost entirely united laterally. The IBr. (axillaries) are almost or quite triangular, 

 somewhat ever twice as broad as long, in lateral apposition with their neighbors and 

 laterally Battened. 



The 10 arms are 150 mm. long and taper rather more gradually than those of 

 A. discoidea. The first two brachials are short, wedge-shaped, the second slightly the 

 longer exteriorly but tapering almost to a point interiorly, the first entirely united 

 interiorly. The first syzygial pair (composed of brachials 3+4) is oblong, two and 

 one-half or three times as broad as long. The next seven or eight brachials are 

 oblong, very short, about four times as broad as long or even shorter, those succeed- 

 ing becoming wedge-shaped, about the same length, and in the distal half of the arm 

 oblong and very short. In the proximal third of the arm the proximal edge of the 

 brachials is somewhat raised, but the remainder of the arm is perfectly smooth. 



Syzygies occur between brachials 3+4, again between brachials 9 + 10 (this some- 

 times omitted) and 14 + 15 or 15+ 1C, and thence at intervals of 7 to 17 muscular articu- 

 lations up to about the middle of the arm, beyond which point syzygies arc rare or 

 entirely lacking. 



Pi is 9 mm. long, broad basally but tapering rapidly and becoming slender and 

 flagellate in the distal half, composed of 30 segments, of which the first eight are 

 broader than long, very considerably so at first, and the remainder are about as long 

 as broad. P 2 is 13 mm. long, stout like Pi in the basal third but tapering rapidly 

 and becoming slender and flagellate distally, with 30 segments, of which the first six 

 are broader than long and the remainder are about as long as broad. The broad 

 lower segments, like those of Pi, are carinate. P 3 is 19 mm. long, much stouter than 

 P! or P 2 but of the same general form, stout basally but becoming gradually slender 

 distally with a flagellate tip; it is composed of 30 segments. P< is 20 mm. long, 

 stouter aixl stiuVr than P 3 with about 25 segments, of which the first 10 are broader 

 than long and those following are about as long as broad becoming slightly longer 

 than broad distally. Like P 3 , P 4 is carinate in its basal half and has a low lateral 

 keel in its outer two-thirds. P 5 is 10 mm. long, about as stout basally as P a but not 

 tapering so rapidly, with 17 segments, of which the first six are longer than broad 

 and the remainder are about as long as broad; the first seven segments are strongly 

 carinate. P, and the following pinnules are 7 mm. long, with 16 segments, slender, 

 about as stout as P, proximally but not tapering so rapidly, the first five or six seg- 

 ments broader than long and strongly carinate, those following about as long as 

 broad, and finally slightly longer than broad. The distal pinnules are 10 mm. long 

 and moderately slender. The carination of the basal pinnule segments gradually dies 

 away at the end of the proximal fourth of the arm. 



Notes.- The specimen from Albatross station 5146 has 16 arms 100 mm. long. 

 Of the six IIBr series present, five are 4(3+4) and one is 2. Tho brachials in the 



