LYON—BLASTOIDEA. 683 
greatest diameter to the summit of the first radials, then 
dually tapering to the column; above the base of the 
pseudambulacral fields, gradually tapering to the summit by 
curved lines; summit truncated, plane. Basal pieces thin, 
then fall to the center of the field in a straight line, thus ie 4 
ing the center of the field a wide, obtuse angle. Ova 
aaa five, large, widely disposed, differing ™ size, 
. . 
