Free-living medusoid hydrozoans can be hard to tell from scyphozoans, but hydrozoan medusae generally have a muscular shelf, or velum , projecting inward from the margin of the bell.
For ‘mouth breathing’ protocols, patients were instructed with a technique aimed at achieving velum closure of the nasopharynx and asked to practice it prior to testing.
This technique allows for closure of the velum , thus excluding nasal NO contamination during expiration.
Its multispiral, heavily sculptured, darkly colored shell, plus its large four-lobed velum , point to a different type of snail, one of the neogastropods.
This fact, together with the fragility of the velum , may cause problems for identification of growth stage and sex of the particular specimen.
Scyphozoan medusae differ from those of hydrozoans in lacking a velum .
The back of the tongue lies opposite the soft palate or velum when the tongue is in a state of rest, and sounds made with the back include velar consonants and back vowels.
Adult heteromorphs show wide velum; the velum in tecnomorphs is narrower.