haplomorpha

from The Century Dictionary.

• In some systems of classification, a group of true craspedote medusans, typical acalephs, or ordinary jelly-fishes, corresponding nearly or exactly with Hydrophora of some and Trachymedusæ of other writers. See Trachymedusæ.
• A division of opisthobranchiate gastropods, of small size and simple form, having no ctenidia, cerata, or other processes of the body-wall. The families Phyllirhoidæ and Elysiidæ represent this division: same as Abranchia .