NIAGARA GROUP. 



205 



Genus S ACCOCRINUS (now. g-en.). 

 [Gr. rfaxxo?, saccus, and xpivov, 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. XLVl. Fig. 1 a-n; and Fig. 2. 



Body large, elongated, sac-foi'm, 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 onel ; 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 



