1 s© 
PALAEONTOLOGY OP NEW-YORK. 
In 1848 the late Edward Forbes published, in the Memoirs of the Geological 
Survey of Great Britain, Yol. ii, Part ii, an article “On the Cystidece of the Silurian 
Rocks of the British Islands ,” in which he redescribed the Genus Pseudocrinites of 
Pearce, and proposed for another one of similar structure the name Apiocystites. 
The essential structure of the body does not differ in these two genera; and it was 
mainly upon the mode of lodgment of the arms in the grooves upon the surface of 
the body, and the peculiar mode of articulation of the ossicula, that the distinction 
was founded. 
I have identified a species of the Genus Apiocystites in the Niagara group, which 
is published in Vol. ii, Palseontology of New-York; remarking at the same time 
upon the close agreement in character between Lepadocrinus of Conrad, and Pseudo¬ 
crinites as described and illustrated by Mr. Forbes. 
In the Genera Lepadocrinus , Apiocystites and Callocystites , the structure and ar¬ 
rangement of the arms and fingers are so similar, that upon the characters presented 
by these alone, no generic distinction could be made. It does not appear to me to 
be fully shown that these appendages in Pseudocrinus are so different from those of 
Apiocystites , as to warrant the establishment of a distinct genus ; and regarding 
fundamental structure as the more important character, I would feel disposed, from 
the knowledge at present possessed, to include Lepadocrinus , Pseudocrinus and Apio¬ 
cystites under one generic term. 
Although the description of Mr. Conrad, published in 1840, was too incomplete 
to enable one to recognize the fossil, yet the figure given in Mr. Mather’s Report 
in 1843 was quite sufficient to attract attention; and I can only suppose that this 
volume had escaped the notice of Mr. Forbes, or he would have made some com¬ 
parisons of this genus and species with the British cystidians described by him in 
1845. 
Following Mr. Forbes in my second volume of the Palaeontology of New-York^ 
I adopted the name Apiocystites for a species in the Niagara group; supposing at 
the same time, with the specimens which were then before me, that I should find 
sufficient distinctions between that fossil and the one under consideration, to sustain 
the Genus Lepadocrinus also. After careful comparison of all the specimens in my 
possession, I am unable to observe any generic distinctions between the Niagara and 
the Lower Helderberg forms. I shall, however, continue the use of the name Lepa¬ 
docrinus, since it has precedence in point of time, and is now pretty well known 
among geologists of the United Strtes. 
The structural differences between the Lepadocrinus of the Lower Helderberg and 
the Apiocystites of the Niagara are not greater than occur in many species of crinoids 
of the same genus, where various modifications take place in the plates of the upper 
part of the body; and even in two specimens of the same species of Apiocystites in 
the Niagara group, there are differences quite as great in the arrangement of the 
upper plates, as between that species and the one now under consideration. 
