porpitidæ

from The Century Dictionary.

• A family of siphonophorans having a circular umbrella without crest and a pneumatocyst which is divided into an octoradiate central part and numerous concentric rings. The gonostyles are provided with mouths, the tentacles have many stalked cnidospheres, and pneumothyræ are present. It contains the genera Porpita, Porpitella, Porpalia, and Porpema.