Clarke, S. F. 1907. Reports on the scientific results of the expedition to the eastern tropical Pacific, in charge of Alexander Agassiz, by the U. S. Fish Commission steamer 'Albatros', from October 1904 to March 1905, Lieut.-Commander L. M. Garrett, U. S. N., commanding. VIII The hydroids. - Memoirs of the Museum of Comparative Zoology at Harvard College 35: 1-18, pls 1-15.