COLLECTING 9 
them the curious little sea-spiders (Pycnogonide), animals which 
seem to be all legs. 
Mollusks, and other classes as well, differ in different latitudes. 
On the rocks of the Northern shores Littorina and Purpura shells 
are very abundant, the latter in various colors and beautifully 
striped. Limpets are also plentiful, but are not as conspicuous, 
since they have flat, disk-shaped shells. When their capture is 
attempted, they must be taken unawares and pushed quickly 
aside, else they take such a firm hold of the rock that it is diffi- 
cult to dislodge them. Near low-water mark under ledges will 
_ perhaps be found chitons, which are easily recognized by their 
oval, jointed shells. On the California coast in like localities 
will be found the beautiful Haliotis, Acmea, and chitons. Every 
stone that is lifted will disclose numbers of little amphipods 
(Gammarus), which will scuttle away on their sides to other 
shelter; worms will suddenly disappear into the mud, and per- 
haps a crab, here and there, having no alternative, will make a 
stand and fight for his liberty. Flat against the stone and not 
easily perceived may be.a chiton, a planarian worm, or a nudi- 
branch. And just below the water’s edge are sea-urchins and 
starfishes, which grow in numbers as the eye becomes accustomed 
to the search. 
The rock pools are natural aquaria, more interesting by far 
than any prepared by man. The possibilities of these little sea- 
gardens are beyond enumeration. The longer one studies them 
the more one finds. In them all classes of seaweeds and marine 
invertebrates may be found and their habits watched. The great 
beauty of these pools gives them an esthetic charm apart from 
the scientific interest they excite. Perhaps one may find here a 
sponge, and removing it to a shallow vessel of sea-water can 
watch the currents of water it creates. Several sponges of the 
same species placed in contact will at the end of two days be 
closely united. If the sponges are of different species they will 
not coalesce. 
In the clefts and crannies of the rocks are various fine sea- 
weeds, often of the red varieties, sea-anemones, hydroids, poly- 
zoans, crustaceans, mollusks, and ascidians. Crabs will be snugly 
