Page:Popular Science Monthly Volume 8.djvu/43

Rh of Biscay, and to a depth of nearly three miles. But, though their existence is proved at these enormous depths, they love best the rock-bound pools left by the retiring tide and the shallow water which fringes our islands and continents; and there they probably attain their greatest beauty and most perfect development.

Their distribution in time reaches back to the earliest dawnings of life upon our globe. The Graptolites of the Lower and Upper Silurian, the Hydroid Medusœ of the Jurassic, the Hydractinea of the Cretaceous, Miocene, and Pliocene, the Serturella of the Pleistocene, and the numberless forms of the present day, are the representatives of this family in geologic and historic time.

Like other humble forms of life, it shows a marvelous persistency. It has lived, almost unchanged, while great dynasties of higher organisms have one after the other risen, developed, and perished, or left only a few meagre representatives among the fauna of the present day. The fragility of their chitinous envelope and the perishable nature of their protoplasmic flesh would, of course, render it impossible that any full record of their existence should ever be found in the rocks of the primeval would, but the fragments which have, here and there, left their impress on the various geologic strata, show them to have been the contemporaries of the oldest forms of life which inhabited the Silurian seas, and to have quietly existed in the depths of those ancient waters over which the great fish and saurian dynasties lorded it through so many centuries.

 

O those on whom the British Association confers the honor of presiding over its meetings the choice of a subject presents some difficulty. The presidents of sections give accounts of what is new in their departments; and essays on science in general, though desirable in the earlier years of the Association, would be less appropriate to-day. Past presidents have discoursed on many subjects, on the mind and on things beyond the reach of mind, and I have arrived at the conclusion that humbler themes will not be out of place on this occasion. I propose to say something of a profession to which my life has been devoted—a theme which cannot stand as high in your estimation as in my own, but which I have chosen because I ought to understand it better than any other. I propose to say something on its origin, its work, and kindred topics. 