Strange appendages on a Garter Snake

[blubird]

Yesterday we watched an adult California Red-sided Garter Snake swimming across a pond near Drakes Beach in the Pt. Reyes National Seashore. The snake was back-lit and swimming directly towards us, so photography was difficult. The attached photos confirmed the ID of California Red-sided Garter Snake, and to my surprise showed what appeared to be fin-like appendages on the side of the head, like "ears". I wondered if this was an artifact, perhaps something foreign stuck to the head, or maybe an adaptation of some scales to help keep the head out of the water. The head never dipped low during the entire swim.