452 
Aug. F. Foerste 
the ray almost reaches the border, is parallel to the latter for a 
distance of 3 mm., and then curves toward the mid-length of the 
left posterior ray, terminating on contact with the latter at a point 
about 4 or 5 mm. from the proximal end of the latter. Between 
the recurved part of the right posterior ray and the adjacent parts 
of the left posterior ray, the intervening part of the posterior inter- 
ambulacral area is reduced to a narrow, curved area, about half a 
millimeter in width, occupied by about two irregular rows of 
plates which are widened in a direction parallel to the rays, attain- 
ing a width of two-thirds of a millimeter. This series continues 
distally as a single irregular row between the strongly curved part 
of the right posterior ray and the much larger plates of the 
border. 
The remaining, and much larger part of the posterior interam- 
bulacral area is bordered for three-fourths of its outline by the 
right posterior ray, only the proximal half of the left outline being 
in contact with the left ray. This part of the area is 8 mm. in length 
and slightly over 3 mm. in width. The anal pyramid occupies 
practically the entire width of the interambulacral area, between 
2 and 5 mm. from the proximal ends of the posterior rays. The 
length of the pyramid is about 3 mm. and its width, 2.5mm. About 
thirteen plates belong to this anal pyramid, converging toward 
the center, but it is not certain that all of them actually reached 
the center. Perhaps five of these plates merely act as supports to 
those lying nearer the center, but this can be determined only 
from other specimens. The interambulacral plates covering that 
part of the area which lies on the proximal side of the anal pyramid, 
all are of very small size. On the distal side of the pyramid, the 
interambulacral plates vary very much in size. The two largest 
attain a diameter of 0.75 mm. The next in size scarcely attain a 
diameter 0.5 mm., while most plates vary between 0.25 and 0.33 
mm. All of these plates are more or less irregularly arranged, the 
two largest plates lying nearer the anal pyramid, along the median 
line of the area. The plates appear to be polygonal and arranged 
in a sort of irregular mosaic. 
Only the distal part of the left lateral ray (No. 2) is present. 
This part is 9 mm. in length. The proximal part of the interambu- 
lacral area between this ray and the left posterior one is scarcely 1 
mm. in width, and is occupied by 3 or 4 irregular rows of polyg- 
onal interambulacral plates, a quarter of a millimeter in diameter, 
