The question which heads this article is not a new one. An old one, indeed, it is; and, common as chalk flints and chalk ventriculites are, it does not show much energy on the part of cretaceous—we do not know how else to single them out—geologists and palæontologists, that this old question has never yet been answered.

The only man who has ever worked properly on the subject is Mr. Toulmin Smith, who many years ago laboured hard and well on these curious organisms, and then retired on his laurels. But Mr. Smith, like all men who have devoted themselves to a special subject, is full of prejudices—we do not mean to say errors—and no progress in our knowledge can be hoped to be made until these prejudices are attacked. Mr. Smith, having built his castle, is not likely to strengthen it until its walls have been undermined, or at least have been battered by the artillery of able antagonists. Dr. Bowerbank is considered to be the only powerful opponent of Mr. Smith's views; but whether the Doctor has expressed his opinions in print or only verbally in ordinary conversation, we do not know; at any rate, the world believes the amiable philosopher of Barnsbury Grove to differ in opinion from the ventriculite-anatomist of Highgate Hill. Mr. Smith believes them to be highly-organized polypidoms, which in their living state were covered over with tentaculated polypes, or that at least were studded with hundreds of tentacle-surrounded heads, ever waving their tiny arms, and catching and feeding upon the tiny prey or on fragments of animal substances which came within their clutch. What Dr. Bowerbank believes them to be we need not say is — sponges.