Hello Flavio,
The Mitra on your website appears to be Mitra nubila Gmelin.  The
listed locality would support that.
The two Vexillum specimens are both members of the
regina/filiareginae/citrinum complex, a rather confusing group.  I
would call the one with the black spiral line Vexillum regina
Sowerby, form filiareginae Cate.  The other one could be the same, or
a related species.
The Tellina looks like Tellina radiata L.  On which coast of Mexico
is the listed locality located?  If it is on the Caribbean side, then
I'd go with Tellina radiata.
Regards,
Paul M.