from the Island of Malta.. 107 
Junior. Antero-posterior diameter 2 inches, transverse dia- 
meter 1,9, inch, height 1,3 inch. 
Description.—We have identified this Urchin with that figured 
by Parkinson in his ‘ Organic Remains,’ not however without 
~ much hesitation, inasmuch as that figure is without details, and 
is moreover drawn from a distorted specimen. We have in vain 
endeavoured to find out the original, and have therefore, from 
the central position of the apical disc and the great divergence 
of the ambulacra, and from its being at the same time the most 
common of all the Maltese Schizasters, and the one most likely 
to have been sent to Parkinson, adopted Defrance’s identifi- 
cation. The test is heart-shaped, its widest part bemg at a 
line drawn across the disc; from this imaginary line the back 
slopes obliquely forwards, and the border is rather bevelled away 
at the cheeks ; from the same line backwards there rises a pro- 
minent ridge which bends over into a short tail-like process. The 
ambulacral areas (3 a) are deeply sunken, the single ambulacrum - 
. has a tapering lanceolate form, and the anteal sulcus is deep and 
narrow ; the poriferous zones lie in the angle of the depression ; 
they consist of twenty-five pairs of holes, of which the outer 
series is the largest ; the length of the petaloidal portion of this 
area from the apex to the fasciole is 1,4, inch. The antero- 
lateral ambulacra (3 a) are more divergent in this species than 
in the other Schizasters met with in the same rocks; they are 
1, inch in length and are slightly curved outwards and back- 
wards ; they make an angle of 35°; the number of pores (3 c) © 
in the zones is respectively thirty-six and thirty-four, the apical 
eight pairs being almost microscopic: the postero-lateral pair 
are ;°;ths of an inch in length and slightly f-shaped; they are 
directed backwards at an angle of 65°, and are proportionately 
narrower than the anterior pair; there are twenty-two pairs of 
holes in each of the zones, the upper six pairs of which are 
microscopic. The peripeta] fasciole (3 4) is distinctly defined and 
passes close to the bases of the petaloid portions of the ambu- 
lacra, but at a short distance from the sides thereof it describes 
a curve inwards in passing over the anterior interambulacra, and 
dips obliquely into the anteal sulcus where it unites with that of 
the-opposite side. The lateral fasciole is large and very distinct ; 
_ it takes a backward and downward course towards the base of 
the posterior border, and joins its fellow at some distance be- 
low the anus; the two fascioles form the letter V in their trajet 
_ on the test. The apical dise is situated very near the centre of 
the back, removed a little nearer to the posterior than the ante- 
rior border ; it is perforated with four equal-sized genital holes. 
The anus is oblong, situated high up in the obliquely truncated 
posterior border, in which is a triangular depression limited on 
