When the edges of the mantle ventral to the inhalant orifice are united, an anterior aperture is left for the protrusion of the foot, and thus there are three pallial apertures altogether, and species in this condition are called " Tripora."
In the Southern Uplands, owing to the greater softness and uniformity of texture of the rocks, rock-tarns are comparatively infrequent, except in Galloway, where the protrusion of granite and its associated metamorphism have reproduced Highland conditions of rock-structure.
Blades forked at the larger end, and separated about one-sixteenth of an inch from each other by winding cotton thread between them, the whole being also bound together by thread, and the protrusion of the points being restricted to one-twelfth of an inch, by which the depth of the incision is limited.
Thus among the tongue movements evoked by stigmatic stimulation of the cortex undeviated protrusion or retraction of the organ is not found.
Thus in the Phylactolaemata the contraction of the muscular body-wall exerts a pressure on the fluid of the body-cavity and is the cause of the protrusion of the polypide.
The mechanism of protrusion in the Cyclostomata is a subject which requires further examination.
The Rotunda, where are the ruins of the old saltpetre works; the Star Chamber, where the protrusion of white crystals through a coating of the black oxide of manganese creates an optical illusion of great beauty; the Chief City, where an area of 2 acres is covered by a vault 125 ft.
Pollination having been effected, and the pollen-grain having reached the stigma in angio sperms or the summit of the nucellus in mnos erms P gY P it is detained there, and the viscid secretion from the glands of the stigma in the former case, or from the nucellus in the latter, induce the protrusion of the intine as a pollen-tube through the pores of the grain.
Mantle with two posterior appendages; ctenidium large and capable of protrusion from pallial cavity.
2), or membranaceous and polished, hairy or smooth, oval or round or bean-shaped, or of some less simple pattern; the valves may fit neatly, or one overlap the other, their hinge may have teeth or be edentulous, and their front part may be excavated for the protrusion of the antennae or have no such " rostral sinus."
The tusks appear externally to the mouth, the form of the upper lip being modified to allow of their protrusion, but are much less developed in females than in males.
Thus a point A will, when excited soon subsequent to point B, which latter yields protrusion of lips, itself yield lip-protrusion, whereas if excited after C, which yields lip-retraction, it will itself yield lip-retraction.
In the Gymnolaemata protrusion is effected by the contraction of the parietal muscles, which pass freely across the body-cavity from one part of the body-wall to another.