Clarence Erwin McClung (April 5, 1870 – January 17, 1946) was an eminent American zoologist and prairie pioneer cytologist who discovered the role of chromosomes in sex-determination.

Wheeler at the University of Chicago and at his suggestion, studied the spermatogenesis of Xiphidium fasciatum, a long-horned grasshopper; launching his scientific career in the research of chromosomes.

Development of the “McClung Model” research microscope and publication of the “Handbook of Microscopal Technique” demonstrated evidence of his commitment to improving the results of scientific research.

He was elected to the American Philosophical Society in 1913 and the United States National Academy of Sciences in 1920.

[5] The University of Pennsylvania conferred upon him at its bicentennial year commencement exercises the honorary degree of Doctor of Science in 1940.