Summing Values Found In A Range

I have the following code with uses a cell color to count the number of cells in a range with the same cell color:

Function CountColor (rng As Range, color as Range) As Long
Dim c as Range
Application.Volatile
For Each c In rng
If c.Interior.ColorIndex=color.Interior.ColorIndex Then
CountColor = CountColor +1
End If
Next
End Function

What I would like is instead of just counting and returning the number of cells of the same color, is for the code to return the sum of the values in the cells of the same colors. Cells being evaluated contain numbers from 1 to 300.