226 Description of a remarkable fossil E'chinoderm. 
vision of the order Echinodermata ; yet, it is thought these aber- 
rant characters are hardly sufficient to entitle them to be classed 
as a distinct group. 
With the Echinideans or Echinides of Goldfuss, they agree in 
three essential characters, viz.: They are composed of ten fields 
(aree); five broad (aree sndj owes, and five smaller (are@ ambu- 
lacrorum); and these are made up of little plates, disposed in 
- rows. Pores or holes run in vertical rows up and down the small 
field (area ambulacrorum). There is, moreover, every evidence 
that the. os inferum and the anus were central, as in the genus 
Kchinus. 
In the following, more inal characters, they. differ from Gold- 
fuss’s description of this group. 
The plates of which the aree majores consist, are mostly six- 
instead of five-angled, and are far more numerous than the ele- 
mentary plates of which Goldfuss’s genera-are made up. 
The plates of the aree majores are arranged, not in single or 
double rows, but in. many rows, varying from seven or eight at 
the widest part, to five or six at the top and bottom. 
The plates constituting the aree ambulacrorum are, doubtless, 
also more numerous, for, though rather obscurely marked; a close ty 
tion shows that there are two kinds, viz., a double vertical 
row of elongated hexagonal plates, interlocking aul connected lat- 
erally, on either side, with three rows of smaller, four-angled, 
Fie rhomboidal plates, (very like the éschars on some spe- | 
cies of Lepidodendron,) making in all, eight 
- rows of plates, arranged as exhibited in fig. 2; ° 
while the corresponding aree of Echinides, ac- 
cording to Goldfuss’s description, are composed 
of but two rows. Each plate is perforated by 
two holes; so that each ambulacrum consists of eight double 
rows of pores. 
No evidence of any kind has been obtained to show whether 
these bodies were pedunculated ; but there is strong presumptive — 
evidence that they were not. This is rendered probable, Ist, 
from their near approximation to the true Echinides; 2d, from 
their gigantic dimensions ; 3d, because no stems have yet been 
found connected with any ow. the specimens ; 4th, because pedun- 
culated Echinoderms of such vast dimensions, would require @ 
much nie stem than is exhibited as any portions of columns 
¥ 
