Page:Natural History, Mollusca.djvu/213

 the Winkle and the state of the atmosphere, and still more, the philosophy of the reason assigned for the habit. The plant-eating Gasteropoda are said to "lay their eggs merely enveloped in a mass of jelly, just firm enough to retain its form in the water, and which, deposited on the fronds of sea-weed, or on the surface of rocks and stones, adheres to them with tenacity. The form of the mass is roundish, oval, or oblong, and it may be more complex in some. The ova are always immersed in the mass, which forms a common bed to the whole; but besides this, each egg (or at most three or four eggs) has its own proper globule of jelly, contained within a skin or pellicle of the greatest tenuity, and which isolates it from the rest."



The accompanying figure, which is copied from Dr. Johnston, represents the mass of spawn laid