29 



primary radials larger than the second, more than twice as 

 wide as long, pentagonal, axillary, and in one lateral ray sup- 

 ports u^jon each upper slojiing side two secondary radials, the 

 last being axillary and supporting upon each upper sloping 

 side two tertiary radials; in the other lateral ray there are three 

 secondary radials, on each side of the third primary radial, 

 the last of which are axillary and bear upon each superior 

 side two tertiary radials, which gives to each of these rays 

 four arms. UiJon the distal side of the third primary radials, 

 adjoining the azygous area there are three secondary 

 radials, and on tlie proximal side two secondary radials 

 the last of which are axillary and bear upon eacli superior 

 sloping side two tertiary radials, which gives to each of these 

 rays three arms. In the ray opposite the azygous area the 

 third primary radial bears upon one side three secondary 

 radials and upon tlie other two secondary radials, the last 

 being axillary and supporting upon each upi)er side two ter- 

 tiary radials, which gives to this arm three rays. It will be 

 observed that this ray is constructed in the same way that the 

 rays are on each side of the azygous area and that the side 

 having three secondary radials is on the side of the lateral 

 ray that has three secondary radials on each side of the third 

 primary radial. This species, therefore, has seventeen am- 

 bulacral openings to the vault. 



There are three regular interradials in each area; one larf^e 

 plate followed by two small ones. They are below tlie ter- 

 tiary radials and do not reach near the vault. There are six 

 plates in the azygous area. The first one is in line with the 

 first primary radials and about the same size; it is followed by 

 three plates in the second range, and two in the third, neither 

 of which approaches the vault. 



The vault is highly convex and has more capacity than the 

 calyx. It is covered with plain, polygonal plates, and bears a 

 rather large proboscis. The ovarian apertures are small and 

 on the sides of the plates surrounding the ambulacral canals. 

 There appear to be seventeen of them. 



This species is distingui.shed by its general form and .seven- 

 teen arms. If the three secondary radials, in one of the 

 lateral rays, is to be regarded as a normal feature, then that 

 alone will distinguish it from all other species. If we had two 



