AUSTIN — ON A NJ!\V GENUS OF ECHINODEKM, ETC. 
447 
Altliougli present during tlic removal of hundreds of tons of lime- 
stone, and diligently and repeatedly searching every bed and ci-anny 
in the locality, I was unable to detect the least indication of a fourth 
specimen. It may thei'efore be inferred that Protoecliinus is of I'are 
occurrence ; and that when the Hook limestone was accumulating at 
the bottom of the Carboniferous sea, it had just appeared on the 
stage of life among the then living echinoderms. 
As far as can be judged from the three specimens procured, I con- 
sider it to be a true echinus, and in all probability the primitive form 
of that now extensively diffused genus. Believing that Protoechinus 
was one of the first, if not the very first true echinus, that appeared 
on our globe, I have adopted the name as suggestive of that fact. 
Observations on the Oenus Palcechinus. 
From specimens of Palsechinus which I have in my cabinet, there 
is great reason to infer that the different species belonging to that 
genus possessed columns similar to the true crinoids, and were 
attached to the ocean-bed as the crinoids were. I had long con- 
sidered this as probable : and, on carefully re-examining my speci- 
mens, I found one in which the indications of the fact are so apparent 
that they almost foi ce conviction that my fu'st surmises were correct. 
In the specimen alluded to the ambulacra are seen terminating at, 
and against, a circular plate with radiating striae on its surface, and 
close along side is a short portion of a column, each of the radii on 
which is a fac simile of those on the body-plate, from which the 
column has apparently been separated, and but slightly displaced by 
the pressure that broke assunder the columnar support, and left it in 
close proximity to its original place of attachment 
I was first led to entertain a doubt about Palsechinus being a free 
echinoderm from finding portions of columns lying close to specimens 
of that genus, and which I could not refer to any known crinoid. 
The striae on the ai'ticulating sm'faces of the circular columnar joints, 
which probably belong to Palaecliinus, are more deeply grooved neai" 
their margin than in Aetinocrinus, or other allied forms. 
Another circumstance that rather favours the supposition that 
Palaechinus possessed a column is the fact that it is occasionally found 
lying on its side, a position the true crinoids are mostly seen in ; and 
as the lower or under side has a larger and more depressed sui'face 
than the rotund, or highly convex, lateral ones, it is a natural in- 
ference that some restraining influence produced this almost uni- 
versal identity of position, and what more probable than that a 
column was the cause of this uniformity ? Of course the presence of 
a column wou^ld prevent the Patechinus, after death, falHng in any 
other way than on its side. Among the numerous specimens which 
I have examined, I have never met more than two that differed in 
