The Museum of Comparative Zoology (MCZ) Library will be renamed today as the Ernst Mayr Library of Comparative Zoology.

The change honors renowned evolutionary biologist Ernst Mayr, 91, Alexander Agassiz Professor of Zoology Emeritus, who has devoted much of his career to the study of the origins of biodiversity.

"It is a great honor and a great pleasure," Mayr said of the name change.

A portrait of Mayr now hangs above the circulation desk of the library in "the most visible place you can have it," according to librarian Eva S. Jonas.

"He is the most outstanding evolutionary biologist of the century," she added.

Among Mayr's prizes are the 1970 National Medal of Science and the 1994 International Prize for Biology.

Much of his fame derives from a ground-breaking investigation into why species differ over time.

Mayr, who retired from active teaching in 1975, said yesterday he has published 20 books and is currently working on two more.

Both Mayr and Jonas also noted Mayr's long-standing contributions to the MCZ, where he served as director from 1961 to 1970.

Mayr says he has arranged to donate his own book collection to the library "someday." The MCZ Library already owns some 250,000 volumes.

Mayr said the library holds special meaning for him. As a student in his native Germany in the 1920s, he said he knew of the museum's fame before he ever heard the word Harvard.

Although he has retired, Mayr said he is still a frequent user of the library.

"I have been going back to my office every day ever since I retired. As I always say, the only difference is the size of my monthly check," he joked.

The opening reception of the Ernst Mayr Library of Comparative Zoology will be held in the library today, from 4:00 p.m. to 6:00 p.m. Mayr said he would give a speech if asked.

"I'll say thank you at least," he said.