BARBADOS-ANTIGUA REPORTS 55 
Carpenter noted that the outer surfaces of the axillaries are 
produced dorsally for a considerable distance beyond the edges 
of the articular faces, as is the case with all the lower bra- 
chials, and they fit very closely against their fellows, their sides 
being flattened and more or less marked by ridges and furrows 
which interlock with those on the adjacent axillaries; these 
furrows are also apparent on the sides of the lower brachials. 
The muscle plates of the axillaries, and in a lesser degree also 
those of the brachials, are greatly thickened, and their upper 
edges are cut out into coarse teeth. 
There is a large food groove on the upper surface of each 
arm and pinnule. The large size of the paired flexor muscles 
uniting the brachials would seem to give the power of rolling 
in the arms very rapidly and completely, while the small, but 
very close and compact, bundles of elastic ligaments on the 
dorsal side of the articular ridges would help in the re-extension 
of the arms. 
In both the larger and better developed trivial and the small- 
er bivial arms a variable number of the lower brachials are 
considerably larger than those which follow, and the passage 
from one type to the other is usually somewhat sudden; on the 
trivial arms there are generally from eight to ten of these large 
massive brachials, but on the bivial there are only about seven, 
six, or even less. The shape of these lower brachials is rather 
variable; they may be roughly oblong, as is the case with the 
first two or three, or their edges may be oblique so as to give 
them a truncated wedge-like form. The more wedge-shaped 
these brachials are, owing to the obliquity of their terminal 
faces, the greater is the inequality in the size of the muscle 
plates on the two sides of the median groove. The pinnule 
socket of these wedge-shaped brachials is on the thickened upper 
edge of the higher muscle plate. The general character of these 
lower brachials is much less regular and symmetrical than is 
the case in other ecrinoids, so that many of them are more or 
less of an aberrant nature. In some few cases the brachial is 
smaller than usual, and triangular, not extending completely 
across the arm, so that the brachials above and below it come 
into contact with one another; sometimes, again, a first brachial 
becomes unusually large. The longest arms seem to have about 
