claek: new geneka of echinoderms 117 



half times as long as the distance from their base to the center of the 

 disk. The size is very large, up to R = 338 mm., r = 87 mm. ; R,: r = 3.9 

 to 4.8:1. 



The abactinal plates are very numerous, irregularly polygonal, 

 largest in the radiating papular areas and along the center of the arms, 

 diminishing in size slightly toward the center of the abactinal surface 

 and very markedly toward the superomarginals bordering the disk 

 and the proximal third of the arms; on the outer two thirds of the arms 

 the abactinal plates are subequal, irregularly polygonal; an irregular 

 carinal row of plates is sometimes traceable from the outer half of the 

 disk along the arms. 



The madreporic plate, which is large, conspicuous, and polygonal, 

 is situated near the center of the abactinal surface and is covered with 

 very fine striae which radiate from the center. 



The abactinal plates are uniformly covered with crowded granules, 

 which are much finer than those on the actinal intermediate plates. 



The papulae are segregated in conspicuous petaloid areas which 

 extend from a central papular region and radiate onto the arms, reach- 

 ing nearly to the middle of the latter. 



Many of the plates in the papular areas bear small pedicellariae, 

 of which there may be as many as three or four on the larger plates; 

 the plates of the interradial areas also bear pedicellariae, though here 

 they are much less numerous. 



The superomarginals increase gradually both in length and in breadth 

 from the center of the interbrachial arc to the arm bases; in the 

 interbrachial arc they are confined to the side wall of the body and 

 overhang the inferomarginals ; on the arm bases they become more 

 recumbent, so that a greater part of their breadth (about two thirds) 

 lies on the dorsal surface. Pedicellariae, sometimes three or four to 

 a plate, occur in the interbrachial arcs, but they gradually become 

 less frequent and are rare in the distal half of the arms. 



The inferomarginals increase in length, but decrease in breadth, 

 from the center of the interbrachial arc to the arm bases. In the 

 interbrachial arc they lie well within the actinal surface, the margin of 

 the body being delimited by the superomarginals; on the arms both 

 superomarginals and inferomarginals reach the same vertical plane. 

 The inferomarginals are slightly shorter than the superomarginals; 

 in the center of the interbrachial arc the two series correspond, but 

 from the arm bases outward the former alternate more or less with the 

 latter. The inferomarginals bear pedicellariae similar to those on the 

 superomarginals, mostly situated near the intermarginal suture. 



Both superomarginals and inferomarginals are somewhat tumid, 

 and both are covered with small closely packed hemispherical granules. 



The actinal intermediate plates are very numerous and decrease 

 in size from the adambulacral series toward the center of the inter- 

 brachial arc; those adjoining the adambulacrals are relatively large 

 and regular in arrangement; within these there is a more or less regular 

 second row which may be traced for about half of the distance to the 



