— ee 
from the Island of Malta. 111 
small Nucleolite before us to the section Pygorhynchus, which 
is thus characterized by Agassiz :—“ Form elongated ; ambu- 
lacra distinctly petaloid, often costated as in Echinolampas. 
Mouth central or subcentral, pentagonal, surrounded with five 
large lobes, and a distinct resette of buccal pores. Anus pos- 
terior, nearer the superior than the inferior border.” All the 
species of the genus Pygorhynchus belong to the nummulitic 
and tertiary rocks ; those of the genus Catopygus, with one ex- 
ception, are cretaceous forms. 
Pygorhynchus Vassalli, Wright, n. sp. 
Test oblong, wider behind than before ; interambulacrum pro- 
duced into a caudal elongation ; petaloid portions of the am- 
bulacral areas narrow and short; sides tumid; anus small, 
round, nearer the inferior border than the dorsum, with a 
projecting beak-like process arching over its upper border, 
and an oblique truncature of the lower part of the border 
below ; base slightly concave ; mouth pentagonal, nearly cen- 
tral; oral lobes small; rays of the poriferous star around the 
margin short. 
Dimensions.—Antero-posterior diameter 1,4, inch, transverse 
diameter ;/,ths of an inch, height nearly {ths of an inch. 
Most of the specimens average only from one-half to two-thirds 
of these dimensions. The large specimen before us is the most 
_perfect we have examined. 
Description.—This small Urchin has an oblong form; it is 
rounded before, a little enlarged towards the junction of the 
middle with the posterior third, which is produced into a caudal 
process. The sides are tumid, and the upper surface is flat- 
tened; the petaloid portions of the ambulacral areas are narrow 
and short, and form only a star on the dorsum ; the single and 
postero-lateral areas are nearly alike in width and length ; the 
antero-lateral pair are rather wider and shorter, they are ths 
of an inch in length, and are slightly curved forwards and 
outwards; their poriferous zones contain eighteen pairs of 
pores, arranged in narrow rows, and not united by any apparent 
slit. The postero-lateral areas are z4,ths of an inch in length, and 
their zones contain twenty pairs of pores ; these areas are directed 
much backwards, which makes the width of the lateral interam- 
bulacra proportionally greater. The apical disc is nearly central, 
but nearer the anterior border; it has four large genital pores, 
and five well-marked eye-holes. The single ambulacrum is almost 
identical in length and width with the posterior pair ; the apices 
of all the ambulacra are rather rounded than lanceolate. The 
lateral interambulacra we have said are very wide, but the single 
