A MONOGRAPH OF THE EXISTING CRINOIDS 89 



dorsal projections on the segments. The pinnules in the proximal portion of the arm 

 distal to the oral pinnules are 4 mm. long, small and weak, with 13 segments of which 

 the first three are about as long as broad and the remainder are somewhat longer 

 than broad, becoming about half again as long as broad distally. The distal pinnules 

 are 7 mm. long, slender, with about 20 segments of which the first is short, not quite 

 twice as broad as long, the second is trapezoidal, about as long as the distal width, 

 and the remainder are about half again as long as broad. The middle and distal 

 pinnules are slightly flattened and subcarinate. The color is dark purple, with the 

 cirri and large lower pinnules lighter. 



The details of the 14 specimens collected by the Siboga at the Aru Islands are 

 as follows: 



(1) 65 arms. Color (in alcohol) yellow, with small circular spots of red-brown 

 on the division series and arm bases; cirri yellow in the proximal half, each segment 

 with a narrow dorsal purple saddle, in the distal half light purple. 



(2) 60 arms. Similar to the preceding; all the division series are 4(3+4). Cirri 

 40 mm. long, with 51-52 segments; the transition segment is about the twentieth. 

 Color purple, darkest on the cirri, with a broad mediodorsal line of yellow on each 

 arm. 



(3) About 80 arms; one of the division series is 6(3+4). Color yellow-brown. 



(4) About 75 arms, about 110 mm. in length. Cirri 37 mm. long. Color yellow- 

 brown. 



(5) 85 arms. Color yellow-brown. 



(6) About 100 arms. Color yellow-brown. 



(7) About 80 arms. Color yellow-brown. 



(8) About 65 arms, about 85 mm. long. Cirri 35 mm. long and composed of 49 

 segments. Color light yellow, concentrically banded with narrow bands of purple; 

 cirri deep purple with occasional large yellow blotches. 



(9) Similar to No. 8. 



(10) 85 arms, 145 mm. long. Cirri 40 mm. long and composed of 52-55 segments. 

 Color yellow-brown. 



(11) 80 arms, about 100 mm. long. Cirri 35 mm. to 37 mm. long and composed 

 of 48-51 segments. P D 32 mm. long, with about 60 segments. Color nearly white, 

 with the cirri and the sides of the division series and arms deep purple. 



(12) About 85 arms. Color yellow-brown dorsally, purple ventrally. 



The preceding Siboga specimens are all very uniform. Division series of 2 are 

 very rare. The proximal pinnules are typically very large and stout basally, tapering 

 gradually and becoming flagellate distally. The distal edges of the segments in the 

 outer half are prominent. 



(13) A young individual with 17 arms about 40 mm. in length. Two of the 

 postradial series bear 2 arms each; two others bear 4 arms each, there being one 

 IIBr 4(3+4) series bearing internally a IIIBr 2 series; the fifth postradial series 

 bears one IIBr 4(3+4) series carrying 2 IIIBr 2 series. 



(14) A young specimen with 14 arms 25 mm. long. One IIBr series is present, 

 which bears 2 IIIBr 4(3+4) series. The synarthry between the elements of the IBr 

 series is just beginning to transform into a syzygy. 



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