Description of a remarkable Sossil Echinoderm. 227 
hitherto discovered in this rock; 5th, all the Echinoderms at all 
approaching the size of this fossil are free bodies; 6th, the absence 
of a pelvis or circular rim for articulation to a stem; 7th, the 
presence of depressions in the position, and apparently for per- 
forming the offices of the anus and 0s inferum. . 
“To sum up, then, with a connected description of the fossil, 
as far as the specimens in our possession will enable us to 
do so:— eet we . 
_ Body ovoid or nearly spherical, free; os inferum central ; anus 
central and above ; are ten, five large (are@ majores), five small 
(aree ambulacrorum); plates of the arese majores mostly 6-sided, 
in many rows; those of the aree ambulacrorum of two kinds— 
one set are elongated hexagons, disposed in double vertical rows 
in the centre of the area, which is elevated into a prominent ridge, 
along the summit of which the interlocking serrated suture of 
this double row is situated ; the other set smaller, irregularly rhom- 
boidal, and running in oblique rows on either side of the former. 
Each plate of the ares ambulacrorum is pierced by two holes ; 
these are central in the rhomboidal plates, but in the hexagonal 
Plates, are situated near. the angle furthest from the before men- 
tioned central suture. Each ambulacrum is thus constituted of 
eight alternating double rows of pores. 
Figure 3, is an outline of a restored repre- 
: Sehtation of the fossil reduced: We propose — 
as an appropriate name for it, Melonites mul- 
Hipora, on account of its resemblance, in gen- 
eral outline, to some species of melon, and the 
‘Sreat number of pores in the ambulacrum. 
This fossil is known amongst the quarry- \ y: 
_ Men, as the “ coltsfoot.”” By reference to SL 
fig. 1, it will be seen that it bears considerable resemblance to the 
_ mpress of the frog of a horse’s foot. This is worthy of note, since 
_ It confirms, in a most remarkable mater, an assertion made in a 
formernumber of this Journal, (1st Set. vol. xliii, No. 1, p. 17,) that 
‘those unacquainted with the science of geology, frequently mis- 
take for fossil footprints, what are, in fact, moulds of shells, or 
_. Merely casual appearances. It also warns the geologist _ —_ 
Hous he should be in inves 
The discovery of this fossil is peculiarly interesting, not only 
_ N aecount of its gigantic dimensions, measuring, as it lies on the 
