In Arca it has a sole-like surface.
In the middle of the year he was sent by the princes to invite Kerbogha to settle all differences by a duel; and in 1099 he appears as treasurer of the alms at the siege of Arca (March), and as leader of the supplicatory processions in Jerusalem which preceded the battle of Ascalon (August).
In Arca too and many others it carries a byssus-forming gland and a byssuscementing gland.
In Ceratisolen legumen, various species of Arca and a few other species the blood is crimson, owing to the presence of corpuscles impregnated with haemoglobin.
For later traditional material, see Buxtorf, De Arca Focderis (Basel, 1659).
The filaments of the gill (ctenidium) of Mytilus and Arca thus form two closely set rows which depend from the axis of the gill like two parallel plates.
In one genus (Planorbis) the plasma of the blood is coloured red by haemoglobin, this being the only instance of the presence of this body in the blood of Glossophorous Mollusca, though it occurs in corpuscles in the blood of the bivalves Arca and Solen (Lankester).
It was during the siege of Arca that Peter Bartholomew, to whom the vision of the Holy Lance had first appeared, was subjected, with no definite result, to the ordeal of fire - the hard-headed Normans doubting the genuine character of any Provencal vision, the more when, as in this case, it turned to the political advantage of the Provencals.
Those of Arca (i, k in fig.
In Arca this can be seen with far less trouble, for the filaments are more easily removed than are the consolidated lamellae formed by the filaments of Anodonta, and in Arca the free axes of the ctenidia are large and firm in texture (fig.