Page:Popular Science Monthly Volume 13.djvu/338

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THE POPULAR SCIENCE MONTHLY.

and, as one of the last was vanishing, the professor imagined that the eye looked back at him with a peculiar and suggestive wink of derision!

The most remarkable representative of the serpent-stars or Ophiurans, as they are called in scientific books, is the "basket-fish," or Astrophyton. The ordinary kinds, as we have seen, have the arms simple; but one genus has the arms extensively branched (Fig. 24). This kind inhabits the deeper waters, and will not be readily obtained except through the aid of dredgers or fishermen, who sometimes bring it up attached to their lines. It attains a diameter of ten or more inches, and the arms go on dividing and subdividing until the divisions are said to number more than 80,000!

If we imagine the Astrophyton with its mouth turned upward, and PSM V13 D338 Crinoid.jpgFig. 25.—Crinoid
(Pentacrinus caput-medusæ),
West Indies.
its arms brought near together, and the ab-oral region furnished with a long, jointed, and flexible stem, we shall have a form not very unlike the Pentacrinus caput-medusæ (Fig. 25), of the West Indies, one of the few survivors of the order of Crinoids that was represented by a great number of species in the palæozoic ages of the earth's history.

Some kinds of crinoids, as the rosy feather-star of the European coast, have a stem in the young state, but at length become detached and live as free crinoids. They thus illustrate, in their embryonic stage, the permanent form of the living stemmed species and of those stemmed forms which fill the rocks in many regions, from the Silurian to the Triassic, inclusive.

It may be remarked here that in no place are fossil crinoids more abundant or varied, and beautiful, than in the sub-carboniferous rocks of this country, especially those in the Mississippi Valley; although larger species have been found in the Triassic rocks of Europe.

While the visitor to the sea-shore may hardly hope to secure a living crinoid, it is well to bear in mind that this form is a near ally of the starfishes, serpent-stars, and the Astrophyton, which he can secure.

It was the remark of one of the old students of Nature that there was nothing on the land that has not its counterpart in the sea. And, if we recall some of the names that have been given to marine forms, we shall see how men have been struck with the resemblances between animals of the land and those of the water. Among fishes we have "sea-vampires," "sea-eagles," "sea-wolves," "sea-hounds," "sea-robins," "sea-swallows," "sea-horses," etc. Among mammals we have "sea-elephants," "sea-lions," "sea-bears," "sea-cows," etc.