51�Թ�

Preoral, prē-ō′ral, adj. situated in front of the mouth.—adv.

The epithelium of the outer surface was probably ciliated, and a portion of it in the preoral lobe differentiated as a sense-organ, with longer cilia and underlying nerve-centre, from which two nerves ran back below the ventral surface.

The preoral lobe persists as the proboscis.

The chief modifications of this form are seen in the Mitraria larva of Ammochares with only the preoral band, which is much folded and which has provisional and long setae; the atrochous larva, where the covering of cilia is uniform and not split into bands; and the polytrochous larva where there are several bands surrounding the body.

The antennae, articulated to the forepart of the head and preoral in position, are long and flexible and consist of fourteen or more segments.