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n. pl. pro·sto·mi·a (-mē-ə)
The anterior portion of the head of an annelid worm, situated in front of the mouth.

[New Latin, from Greek prostomion, mouth, lips : pro-, in front of; see pro-2 + stoma, mouth.]

pro·sto′mi·al (-əl) adj.


n, pl -mia (-mɪə)
(Zoology) the lobe at the head end of earthworms and other annelids: bears tentacles, palps, etc, or forms part of a sucker or proboscis
[via New Latin from Greek prostomion mouth]
proˈstomial adj


(proʊˈstoʊ mi əm)

n., pl. -mi•a (-mi ə)
a small protuberance from the first segment above the mouth in certain worms and mollusks.
[1865–70; < Greek prostómion mouth. See pro-2, stoma, -ium2]
pro•sto′mi•al, adj.
References in periodicals archive ?
Cerebral ocelli are defined here as being located in close association with the brain, within the peristomium or prostomium (excluding the radioles).
websteri exhibit a high degree of morphological plasticity in the palp pigmentation pattern, the shape of the anterior edge of the prostomium, the shape of the major spines on chaetiger 5, and the shape of the pygidium.
Antennae and peristomial cirri are articulated; the antennae have teardrop shaped distal segments and the 3 to 4-segmented peristomial cirri reach to the middle of the prostomium.
Prostomium with a medium antenna originated from the middle zone of the eye pair (Fig.
zulu Specimens One clitellate; Only one, with and their one with clitellum not maturity developing fully developed tubercula pubertatis Characters Length Large, 185 mm abscised Diameter 12 mm 9-11 mm Prostomium Not observed Epilobous, short, broad Number of Abscised, 135 segments not observed Setae Minute, Minute, only difficult to on some segments, detect closely paired Annulation Not described; 4(?
These worms are smooth-bodied and relatively fragile in comparison with other tubificids, with short postclitellar segments and conical prostomium when fixed in alcohol (Fig.
The shell-boring polychaete species were identified on the basis of fifth setiger chaetae, prostomium and pygidium morphology, and branchiae distribution.
The scientific name for this kind of mouth segment is a prostomium, Jacobs explains.
Selected animals were placed in ethanol solution (5%) and dissected to extract the male reproductive organs, located between the prostomium and the clitellum.