Waldo L. Schmitt, 90, curator of biology at the Smithsonian Institution, who was known as one of the institution's 'grand old men,' died Friday at the Friends House nursing home in Sandy Spring after an illness of several months.

A specialist in decapoda, the order of crustaceans that includes lobsters, shrimp and crabs. Dr. Schmitt worked for the Smithsonian for 43 Years before his official retirement in 1957, but continued to work there afterward.

He traveled the world in search of specimens, making his last collecting trip in 1962 to Antarctica, where a 30 - mile series of ice - covered outcroppings is named Schmitt Mesa in his honor.

In the late 1930s, Dr. Schmitt's expert knowledge of the marine life along the coast of South America was brought to the attention of President Franklin D. Roosevalt, when the President was considering a fishing trip to the area.

Of all the voyages and expeditions made by Dr. Schmitt, he said he enjoyed most the one that he and the President made in 1938 to the Galapagos Islands, off the coast of Ecuador.

Dr. Schmitt was born in Washington. His interest in biology and wild - life was nurtured by the works of naturalist Ernest Thompson Seton and weekly hikes with an uncle in search of specimens in Montgomery and Prince George's Counties.

While working at his first job with the Agriculture Department, he began attending George Washington University at night, and earned an undergraduate degree in 1913. He joined the Smithsonian in 1914, and received a Ph. D. from George Washington II, 1922.

At the Smithsonian, Dr. Schmitt became curator of the division of marine invertebrates in 1920, and head curator of the department of biology in 1943. He published more than 70 scientitic papers and was known for helping young biologists and zoologists.

He was a member, founder or officer of dozens of scientific and educational groups.

Survivors include a daughter, Barbara Lundy, of Glenelg, Md., three grandchildren and a great - grandchildren.