Probably every reader will be able to appreciate the above instances of creatures adapted to their surroundings. For there are few people who are not familiar with the common Limpet of the shore between tide-marks, and with the great seaweed called Tangle, which has its habitat a little lower down, and forms great sea-meadows, whose upper limits alone are ever laid bare by the tide. The _Patella pellucida_, too, is fairly common, and the dead shell may be found on most rocky parts of our coast all the year round. As for the blue-striped young shell, floating on the blades of the tangle, those who have leisure to visit the seaside during the months of spring and early summer, may have seen it as I have described it; and the mention of it will recall pleasant memories of clear spring skies, and fresh sea-winds, and fields of heavy tangle swaying gently on the swell that comes in from the open sea. It is interesting to know something of the habits of the creatures whose forms we study, and we have already spoken of the snug little hiding-place that the Semi-transparent Limpet finds for itself in the tangle-root. It is of interest to remember that the Common Limpet, too, is a home-loving creature, which knows and prefers the spot of rock on which it habitually rests; and can find its way back to it, aided by its two eyes and two smelling patches. This has been proved by Professor Lloyd Morgan, who has recorded the result of his observations, made on the coast of Dorsetshire. It is not easy to detach a Limpet from the rock without injuring or exhausting it, but these specimens were caught when moving of their own accord, and were therefore uninjured and brisk. They were removed to short distances, and the following table shows the result of the experiment, clearly proving that the Limpet prefers home, but regards a distance of two feet as a very long journey. ----------+-------------+----------+---------+-------- | | Number | | Number | Distance in | Returned | In Four | Later. Removed. | Inches. | in Two | Tides. | | | Tides. | | ----------+-------------+----------+---------+-------- 25 | 6 | 21 | 0 | 0 21 | 12 | 13 | 5 | 0 21 | 18 | 10 | 6 | 2 36 | 24 | 1 | 1 | 3 ----------+-------------+----------+---------+-------- Similar observations were made at an earlier date, by Mr. George Roberts, at Lyme Regis. Let us now take an instance of adaptation in form. And this time we will take a shell so common that everybody will know it.