Owing to their sedentary habits, quite a representative collection of genera may be made, especially at a spring tide, at any seaside place which is provided with a sandy shore, and with rocks and seaweed. The larger species, however, require to be dredged, and the best time is at night, for then many forms which during the day are concealed in their burrows, will be issuing forth to obtain food. It may be useful to give instances of worms occurring in various situations between tide-marks. Throughout pretty well the whole of the area left uncovered by the tide, even up to nearly high-water mark in many parts of the coast, the cylindrical "castings" of sand and mud, forming little heaps, indicate the burrows of _Arenicola_, the common "lug-worm"; these "castings" have passed through the worm's body, having been {286}swallowed during the process of burrowing as well as for the purpose of obtaining food, as in the case of the earthworms. Rather nearer the water may be seen little tufts of sand-threads, about an inch high, springing from a short piece of cylindrical, sandy tube rising up out of the sand; this is the head end of the tube of _Terebella conchilega_ (Fig. 153). Amongst the rocks may be found loose stones of different sizes; on lifting them up, various kinds of worms may be brought to light, according to the locality, the time of year, the position with respect to the sea, and so on. _Polynoë_ is pretty sure to be present somewhere near low-tide mark; the number of species is considerable, and their colouring very varied: but as the worms have a habit of remaining still on the under surface of the uplifted stone, the observer may easily overlook them. Other worms occur below the stones, more or less buried in the sand or mud; for instance, a small _Nereis_ may be lying in its temporary burrow immediately underneath, and will at once withdraw from the now injured part of the burrow; while deeper in the mud or sand, especially in rather highly-smelling mud, little red worms are abundant, such as _Scoloplos_, _Nerine_, _Capitella_, and others. By digging near low water one may find _Nephthys_, _Glycera_, and others burrowing or hiding in the soil. In rock pools, or sandy stretches amongst rocks kept moist and cool by abundant _Fucus_, one may see under stones the red or yellow gill filaments of _Cirratulus_ and of Terebellids protruding from their burrows and tubes, while other worms are to be met with in clefts of the rocks, and amongst the roots of _Laminaria_.