084 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
almost horizontal; the former supporting an arm, which is free from the 
second plate, the latter two distichals. The succeeding arms are given off 
in exactly the same manner as the first; every second brachial is axillary 
and supports on its shorter sloping side an arm, and on the opposite side 
two brachials of a higher order, until finally near the tips of the arms the 
last axillary gives origin to two arms. In large specimens there are not less 
than fifty orders of brachials to each ray —a very young specimen before 
us has but fifteen, and a somewhat larger one twenty-two — and these form 
straight, arm-like, apparently inflexible trunks, which at the proximal ends 
are four or five times as heavy as the armlets. The plates of which they are 
composed are short, three or four times as wide as long, with crenulated 
apposed faces, the armlets resting against both plates. The inner cavity 
of the appendages is quite large, suboval in outline, the longer diameter 
directed dorsally and ventrally, and the tubes themselves taper but little 
upward. Their ventral side is roofed by a simple row of large, spinous cov- 
ering pieces, somewhat wedge-shaped and alternately arranged, together 
with small, triangular side-pieces, which are united with the brachials and 
covering plates by close suture. First interbrachial as large as the first 
costals, the two plates of the second range but very little smaller, those 
above much smaller and irregularly arranged, varying in the third row from 
three to five, and in the fourth from five to seven, the latter meeting the 
tegminal plates. Tegmen high, contracted in the lower part, then rising 
almost vertically, and rounded near the summit; it is composed throughout 
of small, spinous pieces, sharply pointed at the upper end, and so irregular 
in their arrangement that neither the orals nor any of the other disk plates 
can be identified. At one side ofeach trunk, and always opposite the first 
arm, within the tegmen, there is a large respiratory pore; and smaller ones 
occur along the appendages aside of every arm. Anal tube rather small and 
nearly central. Column of moderate size, the joints so short that at 30 mm. 
from the calyx it contains sixty joints with fifteen internodes. The nodal 
joints very little wider than the intervening ones. 
Horizon and Locality. — Lower Burlington limestone ; Burlington, Iowa, 
and Lake Valley, New Mexico. 
Type in the collection of Prof. Worthen. 
femarks. —This species differs from all others in having but five brachial 
trunks in place of ten, and in having the lower brachials much more deeply 
incorporated into the dorsal cup. 
LONI at He 
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