90 jTirst Annual Report 



Fisher says of it : " This is one of the most beautiful of echinoderms, 

 being characterized by many long thorny spines which are delicate 

 and glassy. It ranges from Monterey Bay to Central America." 



ECHINOIDEA 



Strongylocentrotus franciscanus Agassiz 



This is the large, commonly blackish purple, long spined sea 

 urchin, usually found singly in the lower tide-pools. As Prof. Fisher 

 remarks, it is commonly bright purple or even reddish purple. It 

 is far less common than the following. 



Strongylocentrotus purpuratus (Stimpson) 



The bluish-purple gregarious sea urchin occurs in large colonies 

 in some of the lower tide-pools. One such pool at Mussel Point con- 

 tains a remarkable display of these urchins. Many of them are seated 

 in deep, cylindrical bores in the rock from which it is frequently 

 impossible to extricate them. They apparently do not favor pools 

 that are beyond the reach of low tide spray. 



Dendraster excentricus (Eschscholtz) 



"The common sand dollar of the curio store. It was formerly 

 included in the genus Echinarachnius" (Fisher). The shells of this 

 species are occasional on the beach at Laguna. 



