As Betty Jean said, "beaked" or "having a part that looks like a
beak" is a good literal translation for "rostrata" or rostrate.  More
specifically, as used in conchology, it refers to a specimen in which the
anterior end of the shell is drawn out to an unusual degree, forming a
forward-pointing extension.  The term is most often used in reference to
cowries, which have a tendency to become rostrate in certain localities.
Some cowries, like Cypraea hesitata, are normally rather rostrate, but the
term is most often used to describe individual unusual specimens of species
which are not normally rostrate.  Some rostrate cowrie specimens also have
an extension of the posterior end of the shell, but strictly speaking,
"rostrate" refers to hyperextension of the "rostrum" or anterior end.
        Paul M.