Re: Similar vs. Similarly

>"This glass cameo features an image of the head of Augustus in profile, in a
>similar manner as the stone cameo portrays his wife, Livia (fig. 2)."

Keep it simple, and forget about "similar/similarly".  Perhaps:

"Both cameos feature a head in profile.  The stone cameo (fig. 2)
shows Augustus' wife, Livia, whilst this glass cameo shows Augustus
himself."