Page:The common shells of the sea-shore (IA commonshellsofse00wood 0).pdf/16

6 On one occasion, while engaged in trawling, I had quite an argument with the sailors, they asserting that the sea-grape was only congealed water, and I trying to persuade them of its real character. Finding argument to be useless, I took up one of the grape-like animals, and began to dissect it, telling them beforehand what they would see, and explaining the structure as layer after layer was opened. The men were utterly astounded, and could not get over their surprise for the rest of the day, referring to the subject continually, and having sustained a severe shock in self-esteem.

As is the case with many marine animals, the young are produced from eggs, but when hatched are as unlike their parents as a caterpillar is unlike a butterfly. They very much resemble the tadpole of the frog in shape, and are therefore said to be in the tadpole form. One of these "tadpoles" is shown at fig. 2, as it appears when magnified. When in the tadpole state of existence, it swims freely through the water by means of its long tail; and in order to enable it to direct its course, it is furnished with eyes, which, although minute, are sufficient for their purpose. When, however, it has completed its larval existence, it fastens itself to the substance on which it will ever afterwards rest, the long tail is quickly absorbed, and in process of time it assumes the perfect shape, as seen at fig. 3.

Besides this method of multiplying by means of eggs, the Ascidians also multiply by means of buds, which are pushed out from the parent being, and soon assume similar form and dimensions. A number of incipient buds are seen at the base of fig. 3.

The name of the species which has been figured is Cynthia aggregata.

In Plate I., fig. 5, is a group of Ascidians belonging to the typical genus. This species is called Ascidia mentula, and is perhaps the most plentiful of the British species. It is mostly found at a depth of