420 Mr. W. K. Fisher on new 
c*, Disk-plates small, bearing one to several 
small spinelets; on the ray there is 
only one lateral or marginal spine 
corresponding to the variably spaced 
inferomarginal plates, never a vertical 
comb of conspicuous lateral spines. 
d’, First and second adambulacral plates 
as well as the upper part of the 
second and third ambulacral plates 
united by syzygy (non-muscular 
oe 
. Abactinal skeleton of rays in the 
form of independent, spaced arches 
or costa composed of elongate, 
more or less compressed, over- 
lapping plates, projecting well 
Fig. 1. ; Fig. 2. 
Fig. 1.—Brisinga trachydisca. Oral angle from actinal side. 
Fig. 2.—Ditto. Lateral view of interbrachium, rays removed. 
In all figures: a, first adambulacral plate ; am, ambulacral plate ; 
z, interradial plate; m, marginal plate; 0, mouth-plate. 
above the level of the intervening 
integument and bearing small 
’ spinelets ; intercostal integument 
not fortified by thin, immersed, 
spineless, fenestrated plates. 
J‘. Gonads numerous, in a series 
along either side of each ray; 
the ‘interradial (first) pair ‘of 
adambulacral plates is joined by 
the interradial faces, and above 
them is a united pair of first 
marginal plates —four in all 
(figs. 1 and 2). 
g'. Snbambulacral spines of proxi- 
mal adambulacral plates 
