NIAGARA GROUP. 
225 
Fig. 1 u. The interior of a specimen, preserving thin sharp ridges, marking the direction of the 
grooves to the margin of the plates. The specimen preserves a part of three costal 
and three pelvic plates, with the larger part of two scapular plates. The costal plate 
is a hexagonal one, and its lateral joining edges are marked by fascicles of grooves 
n, n, which proceed from pores in this and the adjoining plates on either side. The 
basal edges of this costal plate, and the two adjoining ones, unite with the basal 
plates along the line marking the greatest width of the fascicles of grooves o, o, 
which are almost continuous ; and the same is likewise true of the junction of the 
scapular plates with the costals, as marked in the line p, p. 
This fragment shows, in a very satisfactory manner, the arrangement of the 
grooves proceeding from the pores; proving the intimate connexion between the 
organs protruding from these pores, if not their continuation from one plate to the 
other in the interior. 
The arrangement of the pores and the little grooves proceeding from them, upon 
the inner side of the plate of Hemicosmites, has been shown by M. Volborth 
(Trans. Imp. Min. Soc. St. Petersburgh, 1S45 - 6). The analogy between this genus 
and Caryocrinus, even in these minute details, is very remarkable; and yet the 
former is destitute of arms, has a lateral ovarian aperture, and a central proboscis. 
These characters show more clearly how near is the Caryocrinus to Cystideans, and 
suggests whether it should not be included in this family. 
Fig. 1 v. This figure represents the structure of this species from the base to the summit of the 
scapular plates, showing one or two of the succeeding plates, and the relative position 
of the arms and the mouth. The latter organ, it will be perceived, is not directly 
over the centre of the hexagonal plate, but a little on one side, and, if the plates 
were brought together, would rest over the centre of the scapular plate on the right 
side of the vertical line*. 
Fig. 1 x. A view of the summit of a specimen, where the plates are well preserved, but the 
form has suffered a little distortion. See similar figure on PI. 49 a, where the form 
of the summit is distinctly triangular. 
Fig. 1 y. The structure of the summit or crown of another specimen, showing the arrangement 
of the plates, arms and mouth, in reference to each other, and to the scapular plates. 
Fig. 1 z. An enlargement of a portion of the column of fig. 1 d, showing the crenulated edges of 
the joints. 
PLATE XLIX A. 
Fig. 1 a. An individual of this species, preserving a portion of the column more than seven 
inches in length. The body is compressed, and has been a long time macerated, so 
that the tubercles and apertures of the pores are not prominent. This specimen is 
interesting, not only as showing the long portion of the column connected with the 
* The mouth has been described as composed of six plates or valves, and this number is all that usually appear. In 
very perfect specimens, however, there will be found an inner series, of three or four plates, protruding beyond the 
others, and alternating with them. One of the six outer ones is usually less conspicuous than the other five, giving 
the appearance of a pentapetalous proboscis. In one example there are three plates in the inner series, and one of 
the six outer ones is elongated to equal and oppose them. 
[ Paleontology — Vol. ii.] 29 
