426 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



PTEKOMETRAUMAGNIPEDA3(A.JH.;Clark) 



Asteromelra magnipeda A. H. CLARK, Proc. U. S. Nat. Mus., vol. 39, 1911, p. 546 (description; 



Albatross stations 5413, 5414); Crinoids of the Indian Ocean, 1912, p. 193 (synonymy; locality). 

 Pterometra magnipeda A. H. CLARK, Unstalked crinoids of the Siboga-Exped., 1918, p. 1943 (in key; 



range). GISLN, Kungl. Fysiogr. Sallsk. Handl., new ser., vol. 45, No. 11, 1934, p. 20. 



Diagnostic features. The earlier cirrus segments do not have overlapping distal 

 ends; the cirri are XXV-XXX, 99-122, the longest 95-118 mm. long, exceedingly 

 long and stout, from one-fourth to one-third again as long as the arms, seldom about 

 as long as the arms; 20 arms 95-100 mm. long. 



Description.- The centrodorsal is columnar, 6 mm. in diameter at the base and 

 5 mm. high, with the dorsal pole elevated into a high truncated conical process about 

 3 mm. high surmounted by a rosette of 5 small radially situated tubercles. The cirrus 

 sockets are arranged in 10 columns of 3 each, the 2 columns in each radial area being 

 interiorly separated by about twice the distance separating the columns of adjacent 

 areas. 



The cirri are XXX, 109-122, from 100 mm. to 118 mm. in length. The first 

 segment is short, and the following gradually increase in length, becoming about as 

 long as broad on the sixth. The succeeding segments are similar or slightly longer, 

 rarely so much as half again as long as broad, in the distal third of the cirri very 

 slowly becoming shorter, in the terminal portion being somewhat over twice as broad as 

 long. Beyond the proximal half of the cirri the segments very slowly become carinate 

 dorsally and develop a projecting distal dorsal edge which is centrally elevated into 

 a small spine; this slowly increases in height, involving more and more of the dorsal 

 surface of the segment until in the very short terminal segments a high carinate spine 

 is found reaching nearly one-half the width of the segments in height, resembling 

 the same structure found in the other species of the genus. The last few segments 

 taper rapidly, as in related species. A more or less marked transition segment occurs 

 between the sixteenth and twenty-second, usually between the eighteenth and 

 twentieth. The ventral distal edge of the proximal segments is slightly everted. 



The IBr series and the IIBr series, the latter 2, resemble those of Asterometra 

 macropoda. The dorsal surface of the division series and lower brachials is evenly 

 and broadly rounded. 



The 20 arms are 90 mm. long, resembling those of Asterometra macropoda, though 

 somewhat more slender basally. 



PI is 8 mm. long, small, slender, and evenly tapering, stiff, with 16 segments. 

 P 2 is 13 mm. long, stouter than PI, with 17 segments of which the distal have produced 

 and spinous distal ends. P 3 is 15 mm. long, slightly stouter than P 2 , with 16 segments. 

 P 4 is 16 mm. long, resembling P 3 . P 6 is 14 mm. long. P 7 is 13 mm. long. The 

 following pinnules are similar, becoming gradually more slender distally and increasing 

 in length to 14 mm. The terminal 4 or 5 pinnule segments have no ambulacral struc- 

 tures and are abruptly smaller and more slender than those preceding, with very 

 spinous distal ends. 



Notes.- The specimen described above was from Albatross station 5413. Another 

 specimen from the same station has 20 arms 90-95 mm. long and the cirri 100-110 

 mm. long with 99-105 segments; the longer cirri are broken at the tip. 



Of the nine specimens from Albatross station 5414 one has 21 arms 95 mm. 



