A MONOGRAPH OF THE EXISTING CRINOIDS 491 



axillary are closely united to their fellows. There are nearly 40 arms 125 mm. long 

 and consisting of about 160 smooth brachials. The first brachials are almost rhom- 

 boidal, relatively long and narrow, and are closely united to their fellows. The second 

 brachials are much shorter and nearly oblong. The first syzygial pair (composed of 

 brachials 3 + 4) is nearly square. The next six brachials are short and nearly oblong, 

 and those following are longer and sharply wedge-shaped with traces of a forward 

 projection alternately on opposite sides as in Antedon brevicuneata. The outer bra- 

 chials become blunter, and squarer and slightly elongated toward the arm ends. 

 The first syzygy is between brachials 3 + 4, the second is from between brachials 

 19 + 20 to between brachials 22 + 23, and the distal intersyzygial interval is 10 to 14, 

 usually 12, muscular articulations. The longest and stoutest pinnules on the arm 

 bases are P 2 and P b ; P 2 consists of about 25 tapering segments and is considerably 

 larger than P b . P 3 and P c are smaller than Fi and P a , and the pinnules of the fourth 

 pair (P 4 and P d ) are still smaller, being the smallest pinnules on the arm. The length 

 of the pinnules following gradually increases but never reaches that of the pinnules 

 of the second pair (P 2 and P b ), and their component segments are not specially delicate, 

 while they are well clothed with perisome up to the arm ends, where the size again 

 decreases. The disk is 12 mm. in diameter and is naked and somewhat incised. The 

 color is blackish, with lighter bands. 



In the type specimen of Antedon laevicirra, which I examined at the Leyden 

 Museum in 1910, the dorsal pole of the centrodorsal is flat and rather broad. The 

 cirri are XXII, 24-28. The eighth-eleventh cirrus segments are very slightly longer 

 than broad, and the last ten or twelve are rather sharply carinate, in dorsal view show- 

 ing an elongate median tubercle. There are 37 arms. The division series are entirely 

 free laterally, though close together. The proximal pinnules resemble those of the 

 slender-pinnuled varieties of Lamprometra palmata. The second and third segments 

 of the lower pinnules are slightly carinate. 



In 1911 I wrote that the division series of this form resemble those of L. palmata; 

 in fact, the whole animal is so much like the slender pinnuled form of palmata that I 

 should not be surprised if the two eventually proved to be identical. The earlier 

 pinnules on the outer side of the outer arms are considerably larger than those on the 

 inner side of those arms, or on the inner arms. 



The three specimens from Siboga station 279 are similar to the specimen from 

 station 248. One has 39 arms about 100 mm. long; P 2 is rather slender, greatly en- 

 larged on the outer side of the outermost arms of each postradial series, and nearly 

 as large on the side of the IIBr series adjacent to the nudradial line. The two other 

 specimens have 37 and 40 arms. 



Of the two specimens from Siboga station 174 one has 39 arms 75 mm. long, and 

 the other has 26 arms 65 mm. long. In both P 2 is markedly enlarged only on the 

 outermost side of each postradial series. 



The specimen from Maratoea has 20 arms 65 mm. long; all the IIBr series are 

 present. 



One of the examples from Paleleh has 33 amis 100 mm. long; the other has 24 



arms 100 mm. long. 



