221 
MUREX curtus. 
TAR. CXCIX.— -F/g*. 5 . 
Spec. Char. Ovate, pointed, subventricose, lon- 
gitudinally ribbed, transversely striated ; aper- 
ture oval ; beak short, recurved ; whorls inter- 
nally striated with elevated lines. 
About twice as long as wide, with 12 rounded undu- 
lations or costae upon each whorl ; the striae are sharp 
and rather distant, they are stronger upon the base ; the 
beak is a little curved and open ; the substance is thin, 
therefore the costae appear as concave undulations within 
the whorl. 
An interesting unique shell from the blue clay of High- 
gate Hill. 
MUREX gradatus. 
TAB. CXCIX.— Fig. 0. 
Spec. Char. Yentricose, longitudinally ribbed, 
transversely striated ; spire short, acute ; costae 
varicose above ; aperture oval, with a short 
expanded beak. 
The enlargement of the costas, which are about 10 in 
each round, produces a square appearance on the upper 
parts of the whorls, which seem to rise above each other 
like steps : the spire is small, and almost slender enough 
to be called mucronate. Width about two-thirds the 
length: the inner lip is smooth. 
From Plumstead. I believe rare, as I have seen but 
one. 
