Due to the kindness of Dr. H. L. Clark of Harvard, we are able now to have some clearer idea about the number of species of sea urchins found at Laguna.
Strongylocentrotus purpuratus Stimp
This is our most common species. It occurs by the hundreds in some of the larger tide pools, such as those near Seal Rocks. Judging from the specimens sent to Dr. Clark, the rather common greenish form, which we supposed to be distinct at first, is simply a younger form of the same species. This greenish form is more often found nearer shore under stones, where quite small individuals are abundant.
Figure 1. Strongylocentrotus purpuratus Stimp. Photo by Miss Clency.
Figure 2. Strongylocentrotus franciscanus A. Agassiz. Photo by Hamilton.
S. franciscanus A. Agassiz
These larger urchins are not so common as they may have been. Larger specimens may be obtained under rock ledges in deep water. Smaller forms of the same species, which seem to have long reddish spines, may be found in the tide pools, but are not common.
W. A. H.