NIAGARA GROUP. 
205 
Genus SACCOCRINUS (nov. gen.). 
[Gr. (fuxxos, saccus, and jcpjvov, lilium.) 
Pelvic plates three ; costal plates five, very large, succeeded by a second, third and fourth 
series of costal and intercostal plates ; scapular plates double or in conjunction, and the pairs 
separated by a wide interscapular plate ; arm-joints of each pair succeeding the scapular plates, 
and separated by a single small plate ; arms composed of a double series of plates, originating 
in pairs, from distinct arm-joints, each arm bifurcating, two, three or more times. 
595. 1. SACCOCRINUS SPECIOSUS (n. sp.). 
Pl. XLVI. Fig. 1 a-n; and Fig. 2. 
Body large, elongated, sac-form, gradually enlarging from the base ; pelvic plates not well 
ascertained ; first costals large, pentagonal or hexagonal, one or two probably heptagonal; a 
second, third and fourth series of costal plates with intercostals in the two higher series, making 
respectively ten and fifteen plates in each one'?; second series of costal plates apparently with 
one or two large supernumerary plates, making six or seven plates ; scapular plates double or 
in pairs, placed directly over the summits of each first costal plate, and supporting a pair of 
arms, which, above the second-or third joint, are composed of a double series of joints slightly 
interlocking with each other ; column round, composed of alternating larger and smaller joints, 
the larger ones sometimes nodulose on the margins ; surface of the body finely granulate. 
It is with some difficulty that the characters of this species have been made out. Several of 
the plates in the centre of figure 1 a are much broken and mutilated : the pelvic plates are 
broken off. When first discovered, this individual was nearly entire, with five or six inches of 
the column attached, but was subsequently broken before its characters were studied. The 
specimen fig. 2 is certainly of the same genus, if not specifically identical, and from this one 
we are able to establish the fact of three pelvic plates. The two specimens, apparently, present 
opposite sides to view, and both are much injured in the plates of the third and fourth series, 
which have been restored as far as possible from the fragments remaining. There are clearly 
five series of plates from the base to the commencement of the scapular plates, which are 
arranged in pairs, giving origin to ten arm-plates ; the arm-plates of the same pair are separated 
by a small intercalated plate, which supports two other smaller plates, and these a second 
series of the same number, beyond which the structure has not been traced. These plates are 
between the arms of one pair ; and between the arms of different pairs there is a wider separa¬ 
tion, produced in the first place by a wide interscapular plate, which sustains several other 
plates in successive series, which have not been fully traced. A large arm-joint rests on each of 
the scapulars, succeeded by one or two simple joints, above which the arms are composed of 
a double series of joints. The arms of this species divide in a very peculiar manner, necessarily 
quite different from the bifurcation of arms composed of a single series of plates, which divide 
