Houghton, Mifflin and Company, Boston
In March, 1864 Henry Oscar Houghton established a publishing company
with Melancthon Hurd (who had preciously been with Sheldon & Co.)
named Hurd and Houghton.
In 1872 George H. Mifflin became a partner. In 1878 the company of
James R. Osgood and Co. merged with Hurd and Houghton and the new firm
was Houghton, Osgood and Co. with partners Henry O. Houghton, George
H. Mifflin and Lawson Valentine.
For more details see: 19th Century Juvenile Series - Hurd and Houghton
In 1880 Osgood left the company and the new outfit was Houghton, Mifflin and Company.
Houghton, Mifflin and Company had an extensive booklist which included the likes of Nathaniel Hawthorne, James Fenimore Cooper and Harriet Beecher Stowe. It juvenile series list however was relatively short.
Here are the juvenile series published between 1880-1900: