246 Mr.F. M‘Coy on some new Paleozoic Echinodermata. 
diatingly marked at their margins. Length of cup 84 lines, 
width 6 lines, length of rays 2 inches. 
Of the arms visible one has but four joints, one has seven, and 
the other three visible have six each. This species differs from 
the P. radiatus (Aust.) by the slighter radiation of the plates, the 
greater proportional width of the cup, the articulation of the arm- 
joint extending the full width of the scapule, the latter distine- 
tion being very striking as well as the consequent greater strength 
of the rays. The surface seems obscurely granulose, but is not 
distinctly preserved. 
Rare in the carboniferous limestone of Hook Head, co. Wex- 
ford. 
(Col. University of Cambridge.) 
(Inarticulata.) 
Platycrinus vesiculosus (M‘Coy). 
Sp. Char. Body spheroidal, depressed ; visceral portion hem1- 
spherical, deeper than the cup; pelvis pentagonal, small, flat- 
tened ; scapule small, rotundato-quadrate, one-third wider than 
long, very thick, gibbous, slightly concave in the centre, lower 
edge hanging below the pelvis, excavation for the first arm- 
joints very small, round, marginal, less than one-third the 
depth of the scapulee ; visceral plates very large, irregular, po- 
lygonal, some of them nearly equalling the scapule in size, 
they are moderately convex, and each rendered rugged by se- 
veral small tubercular projections ; mouth lateral, surrounded 
by small plates. Length of small specimen from pelvis to 
vertex 6 lines, width 8 lines. 
The very large, bubble-like tuberculation of the visceral plates 
and the small, gibbous scapule give a most peculiar aspect to this 
species, quite unlike any other I am acquainted with. I find 
the characters very constant. 
Not uncommon in the carboniferous limestone near Bakewell, 
Derbyshire. 
(Col. University of Cambridge.) 
Platycrinus diadema (M‘Coy). 
Sp. Char. Body very much depressed, spheroidal (from the base 
of pelvis to the vertex one-third less than the diameter between 
the arms) ; pelvis large, depressed, pentagonal, without divi- 
sional lines columnar adherence circular, crenated, one-third 
the diameter of the pelvis, but seated in the bottom of a deep 
circular excavation three-fourths the diameter of the pelvis; 
scapule hexagonal, nearly twice as wide above as below, about 
one-third wider than long, very slightly convex except at the 
