260 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



altogether invisible in lateral view and are often comparatively large and granulated 

 externally. The IBri are short, broad, and laterally united, forming more or less of a 

 prominence at the middle of their junction with the broadly pentagonal IBr 2 (axillaries) . 

 The postradial series divide twice and sometimes three times. The IIBr series are 

 4(3+4) and the IIIBr series, when present, are 2. The dorsal surface of the elements 

 of the division series is often considerably arched. The arms vary in number from 11 

 (probably even 10) to 25 or more; they are 100 mm. long and may have 180 brachials. 

 The first six or eight brachials are relatively short and broad, nearly oblong in outline, 

 and often much rounded dorsally. The following brachials are more triangular, with 

 a variable tendency to overlap dorsally, and their broader ends project alternately on 

 opposite sides of the arm to a greater or less extent. Farther out they become more 

 quadrate again, but remain relatively short and broad and more or less overlapping 

 until almost the very end of the arm. The first brachial syzygy occurs between brachials 

 3+4, and the second from between brachials 11 + 12 to between brachials 16+17; 

 the distal intersyzygial interval is 7-13 (usually 10 or 11) muscular articulations 



The first pinnules are comparatively small and consist of about 20 short seg- 

 ments of which the lowest are broad and slightly carinate. P D , if present, is smaller 

 than PI, and so is P a . The following pinnules may reach nearly 15 mm. in length, 

 with as many as 25 segments, which are both longer and stouter than in the lower 

 pinnules. The relative sizes of the pinnules vary greatly. In the outer arm from 

 each IIBr series the largest pinnules are generally P 2 and P b , but on the inner arm the 

 largest pinnules are P b and P 3 (on the seventh and eighth brachials), while on arms 

 borne directly on the IBr axillaries P 3 and P c are usually the longest. All but the 

 lowest of these large pinnules have strong and blunt lateral processes at their distal 

 ends. The pinnules of the next pah 1 are generally considerably smaller, with rela- 

 tively shorter segments, which gradually become more elongated in the slender distal 

 pinnules but lose the lateral processes at their ends. The disk is 10 mm. hi diameter 

 naked, and much incised. The sacculi are small but abundant. The color in alcohol 

 is ashy gray, white, or pale flesh color, with frequent bands or patches of purple or 

 yellowish brown ; sometimes purple with whitish bands. 



Carpenter said that this is in some respects the most remarkable species of 

 Antedon that he had seen, for it has a very considerable range of variation and has 

 been described under four different names. He called it Antedon variipinna, but 

 unfortunately the type specimen of variipinna from Borneo represents quite a different 

 species with cylindrical instead of sharply prismatic lower pinnules. 



He said that the Challenger collection contained two individuals from the entrance 

 to Prince of Wales Channel in Torres Strait that agree with the type of crenulata in 

 several points, but they have no IIIBr series at all. One of them has spines on 

 the distal cirrus segments though the cirri of the other are merely carinate. At 

 first sight, he said, it did not seem advisable to unite these two forms under one 

 specific name, since one had IIIBr series and the other lacked them. He therefore 

 gave the Challenger specimens the manuscript name bidentata, which he later sup- 

 pressed. He remarked that the same course was taken two years later by Bell who 

 described Antedon decipiens with spiny cirri and no IIIBr series, and A. irregularis 

 with unarmed cirri and IIIBr series. But their other characters, he noted, especially 

 the short brachials and the lateral projections on the lower pinnules, agree very 



