Dyers Compendium lists the unit as 1st Regiment Mounted Rifles "sometimes designated 7th New York Cavalry. First organized at New York City as 2 companies A and B for duty in the Dept of Virginia and mustered in at Fortress Monroe, Va July 30 1861. Attached to District of Forttress Monroe. Dept of Virginia, to May 1862. Unattached Dept of Virginia to July 1862. Unattached , Division at Suffolk Va. 7th Army Corp Dept of Va to April 1863.

Service. Duty at Fortress Monroe and at Camp Hamilon Va till May 1862. Action in Hampton Roads, Newport News, March 8-9 1862, between"Monitor' and Merrimac." Howards's bridge April 4 (Cos. A and B). Near Lee's Mills April 5 (Cos A and B). Tranters Creek, Norfolk Va., May 10. Suffolk , Va. May 14. Reconnoissance to Edenton. N.C. May 27 - 31

Dyers has almost a whole page about the 7th New York.
Hope this is helpful.