"The Countess reined in her stamping mare"

Creative Commons Attribution Share AlikeMare - Credit: Überraschungsbilder
This is interesting.  The horse appears to be angry; in many legends and fables, horses represent wisdom and the unconscious.  Carl Jung wrote that horses relate to the 'mother' archetype; their position as 'lower' than man in the hierarchy endows them with a "surge of instinct", which he argued was closely related to the maternal impulse.  In some Celtic iconography, mares are depicted as symbols of fertilty.  The only Celtic deity to be adopted by the Romans was the goddess Epona, which means 'Great Mare' in the Gaulish language.  The Welsh goddess Rhiannon is thought to be an aspect of her.  In the title story of 'The Bloody Chamber', Maman's horse seems to be as determined as she is to reach the narrator in time.  The fact that the stepmother archetype in 'The Snow Child' sits atop an angry mare does seem to be an invocation of maternal rage at the cruel treatment of the girl.