Subtle shades of blue

Eric has been finding some very nice chitons lately.  This individual was discovered in a Bull Kelp holdfast and was only ~1 cm long.  When photographed under a microscope the subtle shades of blue became easier to discern.

Here's a fun thing to look for in the picture below.  The head valve and tail valve are slightly different shapes, but sometimes it's hard to know which is which.  In this case, the central points on the middle valves point backwards.  So can you tell which is the head end and which is the tail end?  (Answer below the picture.)

 

(The head valve is on the right and the tail valve is on the left.)

To appreciate some of the colors and patterns, the next image shows a close-up of the middle valves (click on the image for a large version):

 

The photograph below shows a close-up of the edge of the girdle, the fleshy portion surrounding the valves:

 

I'm still working on the identification of this chiton.  Perhaps it's a species of Cyanoplax?  If you have any thoughts about its identity, please let me know!