Monograph of the Shallow-water Starfishes of the 



North Pacific Coast from the Arctic Ocean to 



California, with Revisions of Various Extra- 



limital Genera and Species. 



BY 



ADDISON EMERY VERRILL, 

 Professor Emeritus of Yale University. 



INTRODUCTION. 



RICHNESS OF THE STARFISH FAUNA; CAUSES. 



THE Northwestern Coast of North America seems to be the head- 

 quarters or metropolis of shallow-water starfishes. No other region, 

 so far as known, has anything near so many species, nor so many 

 generic and family types, in shallow water, nor so great an abun- 

 dance of individuals. 



The species and genera confined to the deeper waters off these 

 shores seem to be equally numerous, or more so. 



At present there are over one hundred shallow-water species 

 known from that region, besides about twenty named varieties. 



The abundance and variety of starfishes in these shallow waters 

 is apparently greater than at Panama, the West Indies, or the most 

 favorable parts of the East Indies in similar depths. 



This profusion of starfishes does not hold good for the other 

 classes of Echinoderms. The Sea-urchins (Echinoidea) are repre- 

 sented by comparatively few species, of which only about five are 

 common, and those belong to widely distributed genera. But this 

 is about the normal number for any similar cold-water fauna. 



The serpent stars (Ophiuroidea) are represented by about the 

 usual number of species, none of them of unusual types. 



The Crinoidea are represented in shallow water only by a single 

 large, comatulid species, so far as known to me. 



The Holothurians are numerous, but not remarkably so, and 

 mostly of common genera. 



This coast seems admirably adapted for the permanent occupation 

 and evolution of starfishes, and similarly for certain groups of other 

 marine invertebrates and fishes. 



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