Mike
That research was done over 20 years ago and I do not remeber the exact citation. But I believe that I took that information from the lesser known Naval Official Records regarding the movements of the CSS Ponchartrain.
The Ponchartrain was not a part of the Confederate Fleet at Island #10 because of its assignment to go to Little Rock. On the way south is when it picked up the two #32 pound rifled guns and the Battery of Artillery from Fort Randolph.