A member of the staff of the Los Angeles County Museum describes a technique used in the building of a mount for a fossil sea lion. Steps discussed and illustrated include; the wooden armature, the fiberglass rib-case shield, the completed fiberglass armature, the main support of the mount, secondary armatures, attaching the secondary armatures to the main armature, the com pleted mount, laminating fiberglass, controlling strength in fiberglass, and fiberglass rods. -- AATA