Hello, Lebaron. I took a guess at Reynders, and came up with the following;
John Reynders & Co. (John and Charles Reynders; John Reynders sells to Charles Reynders and William Harz) surgical, veterinary, and orthopedical instruments; skeletons and anatomical preparations
1879-82: 303 Fourth av
1883-85: 303 Fourth av and 164 W. 27th
1886-1900: 303 Fourth av and 314 E. 22d
Source: American Surgical Instruments: American Surgical Instruments: An Illustrated History of their Manufacture and a Directory of Instrument Makers to 1900 by James M. Edmonson, Ph.D., Curator, Dittrick Museum of Medical History, Cleveland Medical Library Association and Case Western Reserve University.
Regards, Lou