8 USC 1304(e):
(e) Personal possession of registration or receipt card; penalties
Every alien, eighteen years of age and over, shall at all times
carry with him and have in his personal possession any certificate
of alien registration or alien registration receipt card issued to
him pursuant to subsection (d) of this section. Any alien who fails
to comply with the provisions of this subsection shall be guilty of
a misdemeanor and shall upon conviction for each offense be fined
not to exceed $100 or be imprisoned not more than thirty days, or
both.
and
8 USC 1306(a):
a) Willful failure to register
Any alien required to apply for registration and to be
fingerprinted in the United States who willfully fails or refuses
to make such application or to be fingerprinted, and any parent or
legal guardian required to apply for the registration of any alien
who willfully fails or refuses to file application for the
registration of such alien shall be guilty of a misdemeanor and
shall, upon conviction thereof, be fined not to exceed $1,000 or be
imprisoned not more than six months, or both.