umboniform a. [L. umbo, knob or boss; forma, shape] 1. Like or shaped like an umbo. 2. (MOLL: Gastropoda) Having a low blunt or rounded spire, nearly lenticular in shape. see rotelliform.
umbonuloid a. [L. umbo, knob or boss; Gr. eidos, like] (BRYO:
Gymnolaemata) In cheilostomates, autozooids having frontal shields formed by calcification of the basal side of the epifrontal fold.
umbo-veliger (MOLLL:Bivalvia) In oysters, the last larval stage.
umbraculate, umbraculiferous a. [L. umbraculum, sunshade] Bearing an umbrella-like structure or organ.
umbrella n. [L. dim. umbra, shade] 1. Any umbrella-shaped structure. 2. The ectodermal cells located anterior to the preoral band of cilia in the development of a trochophore larva. 3. (CNID: Scyphozoa) The deep to shallow bowl like body of a medusa or jellyfish; the bell. see exumbrella, subumbrella. 4. (MOLL: Cephalopoda) The velum or interbrachial web interconnecting the head and arms of the finned octopods.
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