1 The highest monthly average temperature in Keystone for July is 54 degrees. 2  The lowest monthly average temperature in Keystone for December is 14 degrees. 3  The most monthly precipitation in Keystone occurs in January with 0 inches.  The air quality index in Keystone is 15% better than the national average.
Simple eye in invertebrates. A simple eye (sometimes called a pigment pit) refers to a type of eye form or optical arrangement that contains a single lens. A simple eye is so called in distinction from a multi-lensed compound eye, and is not necessarily at all simple in the usual sense of the word. The eyes of humans and large animals, and camera lenses are classed as simple because in both cases a single lens collects and focuses light onto the retina or film.
The parietal eye is a tiny, transparent scale on the top of the head that detects light and dark. Iguanas use the parietal eye to alert them to aerial predators. It is sometimes referred to as the third-eye. The photos below show the femoral pores of a male iguana (Jake). The photo on the left was taken when Jake was not in breeding season.