252 Mr. F. M‘Coy on some new Paleozoic Echinodermata. 
or more rows of interambulacral plates, instead of two as in those 
of the newer rocks and existing seas ; as therefore those sea-urchins 
differ from all of the order Echinida in the great number of rows 
of plates in the test, usually having an odd number of rows in the 
interambulacra, and the consequent impossibility of theoretically 
dividing them at the sutures into five equal parts, I would pro- 
pose to form a peculiar order for their reception under the above 
title, indicating the complexity of thei structure. I first drew 
attention to the structural peculiarities of those fossils in 1844 
in my ‘ Synopsis of the Carb. Limest. Fossils of Ireland’ (p.171 
to 174), where I gave the generic characters of the genus Pale- 
chinus (proposed in manuscript by my friend Dr. Scouler), and 
described and figured several species having from three to five 
rows of plates in the interambulacra. In the same work I stated 
that the plates of the so-called Cidarites of the carboniferous 
period being hexagonal was a proof that they too must have had, 
like the Palechini, more than two rows of interambulacral plates, 
and being consequently distinct from the newer fossil and recent 
Cidaris, | mentioned that I had long distinguished them in 
manuscripts (in the collections at Dublin) under the name of 
Archeocidaris. In that work I withdrew my own name however 
in favour of Echinocrinus, by which M. Agassiz had announced 
his intention of designating the carboniferous Cidaris Neri, &e. 
in his Introduction to the 2nd livr. of his ‘ Monog. des Echinod. 
Fossiles, p. 15: although he did not either define the genus 
or recognise the aforesaid peculiarities, the name itself seemed 
to indicate an entirely different affinity, namely with the Cri- 
noidea, in which group this generic name is placed in Agassiz’s 
‘Nomenclator Zoologicus.’ I propose to resume now my old 
name for this genus, Ist, because M. Agassiz neither mdicated 
the affinities nor gave any descriptive notice of the genus Echi- 
nocrinus, while I have done both for my Archeocidaris ; 2nd, se- 
veral of the continental geologists have not followed my example 
in rejecting my own name, but prefer Archeocidaris ; 3rd, in the 
‘ Catalogue Raisonné des Nchinodermes,’ &c., published by MM. 
Agassiz and Desor in the ‘ Annales des Sc. Nat.’ for November 
1846, no mention is made of the genus Hchinocrinus, but the 
species which were to have formed the type of it (Cidaris Nerit, 
&c.) are given under the new title of Paleocidaris, which of 
course has no claims for adoption on the score of priority; nor 
do MM. Agassiz and Desor even there seem aware of the pecu- 
liarity in form of the interambulacral plates or their abnormal 
number, although my observations on those points are mentioned 
by M. Verneuil nearly two years before in his ‘ Coup d’ceil général 
sur la Faune Paléozoique de Russie,’ prefixed to the second vol. 
of MM. Murchison, Verneuil, and Keyserling’s great work on 
