NIAGARA GROUP. 
233 
CYSTIDEiE. 
There are certain peculiar fossil bodies, which, from their general structure and habit, have 
usually been arranged with the Crinoideae ; but to which the name of Cystideae has been given 
by M. Von Buch*, who regards them as forming a distinct order of Echinoderms, inferior to 
the Crinoids. They approach the Crinoideae in some of the genera, and depart widely from that 
family in others. Among the obvious characteristic distinctions we may mention that the genera 
of cystideans have the entire body more or less spherical, and entirely covered with polygonal 
plates, except at several points where there exist apertures connected with important functions 
of the animal. One of these apertures near the summit is the mouth, and near it is an anal 
aperture or pore ; but the most conspicuous one is the ovarian aperture, which is situated below 
the summit, on the posterior side of the animal. The arms are either absent altogether, or very 
much modified in their character, when compared with those of the Crinoidea proper. Instead 
of originating from the higher plates of the cup, which are gradually changed in form, or the 
interstices filled with smaller plates, the cystideans are entirely enclosed ; and the appendages 
representing arms are spread over the summit, originating from near the mouth, and extending 
down the sides to a greater or less distance ; or represented only by a few oral tentacula. These 
arms in many species consist of a double series of joints, separated from each other by a 
groove, and the whole resting in a depression upon the surface of the plates or along their 
joining edges. These representations of arms appear like a surface ornament, but they are 
readily separated from the plates, and are shown to be composed of joints of unequal size. At 
certain points upon these arms there arise jointed tentacula, not very dissimilar to those of 
some Crinoidea ; so that the surface is ornamented with several rows of tentacula, diverging 
or radiating from the summit. 
These arms and tentacula are not present in all species : indeed they were at first supposed, 
by Von Buch, to be destitute of arms altogether; and some of the species possessing these 
appendages may have them entirely removed', leaving no positive evidence of their having 
existed, beyond the shallow groove in which they are imbedded, and even this is sometimes 
obliterated-)-. 
* Uber Cystideen, &c., by Leopold Von Buch : Transactions of the Royal Academy of Sciences of Berlin. Trans¬ 
lated and published in the Quarterly Journal of the Geological Society of London, Vol. ii, part 2, page 20, with two 
plates. This memoir should have been cited under Caryocrinus ornatus. 
t The Cystideae were described by Von Buch as being entirely destitute of arms, and in this respect they would 
show an important deviation from the Crinoide®. M. Volborth, on the other hand, maintains that the Cystideae all 
have arms, and that they are true Crinoideae. His argument is as follows: 
“ All the Cystideae, like Crinoideae, were provided with articulated arms; and this statement is not mere hypothesis, 
“ but the result of philosophical induction from distinct well grounded facts, determined by observation, from the 
“ presence of arms in some species, and the presence of tentacle furrows in others. The Cystideae are likewise true 
“ Crinoids. Either in the young state, or throughout life, they were attached by an articulated stalk, or by a pedicle, 
“ either to the bottom or to foreign bodies. They had articulated arms, which, as in Crinoideae, proceeded from the 
[Paleontology — Vol. ii.] 30 
