27 



rays support on each upper sloping side three secondary radials, 

 which gives to each of these rays two arms. In each ray adjoin- 

 ing the azygous area there is on each superior sloping side of the 

 third primary radial a single secondary radial, which is axillary 

 and supports on each side three tertiary radials, which gives to 

 each of these rays four arms. There are, therefore, fourteen arms 

 in this species. The calyx is much more protuberant at the ends 

 of the radial series adjoining the azygous area than elsewhere, by 

 reason of the increased number of radial plates. The arms are 

 composed of a double series of short plates, from the commence- 

 ment united by the usual zigzag suture. 



There is a single long twelve sided plate in each regular inter- 

 radial area. It rests between the superior sloping sides of the 

 first primary radials, where it is concave, to conform with the 

 other plates adjoining. It then curves over the summit of the 

 calyx, where it is very tumid and separates the primary, secondary 

 and tertiary radials and unites with two plates belonging to the 

 vault. There are four plates in the azygous area. The first one 

 is in line with the first primary radials and slightly longer and 

 narrower than either of them. It is followed by three plates, the 

 middle one of which is narrow within the concavity of the calyx, 

 but gradually expands as it curves over toward the vault and be- 

 comes wider than the lateral plates at its union with the three 

 plates belonging to the vault. The lateral plates are wide within 

 the concavity of the calyx and very tumid where they curve over 

 toward the vault, but become narrow and flattened where they 

 unite with the plates of the vault. 



The vault is highly convex, and interradial areas concave. There 

 is a large, tumid plate at the apex of this vault, which is sur- 

 rounded by six large, convex plates and from two to four small 

 plates in the azygous area. In some of our specimens there are 

 only two of these plates at the top of the azygous area, that sep- 

 arate it from the summit plate, as shown in figure 2, and in others 

 there are four, which is the case in the specimen illustrated by 

 figure 3, but they are hidden from view, in the illustration, because 

 of the prominence of the azygous swelling. A row of large tumid 

 plates covers each ambulacral area from the summit to the arms 

 and there are two of these plates at the base of the arms in each of 

 the four armed series. It would seem that the ambulacral canals 

 are covered with large plates where they unite in each radial 

 series. The plates in the interradial areas are flattened or con- 

 cave and more or less elongated. The azygous area is very wide 

 and bears an elongated, more or less elliptical, bulbous promi- 



