of the animal. The foot of the 双壳纲 is a fleshy process adapted by its form to digging rather than to locomotion.头足类的神经系统是除了嵴椎动物以外的有体腔动物当中最复杂的。头足类的外套膜有的巨大神经纤维是神经生理学最合适的实验材料。
Formation of mollusc shell.In shelled molluscs, the mantle is the o