Note 11 — Chapter II · THE METEORS OF THE SEA.
Reading edition
Page 16. The Physophoridæ include the interesting forms, Physalia (Portuguese Man-of-War), Porpita, Vellela, etc. The first named indicates the character of the group, as its fleshy mass is surmounted by a beautiful bladder-like float, a mere bubble of membrane. These forms are not often seen out of tropical waters.