1918 Bush: on Echinodervis 19 



and articulate like those of scissors. Pedicellariae with several valves 

 may also occur; these are described with the species to which they belong. 



The Ophiuroidea (brittle stars) are not numerous in the region in- 

 cluded. They are usually found by trawling. Ophiura aculeata is the 

 most common species. It is often found on the holdfasts of the common 

 kelp (Nereocystis). Amphioplus abditus, a very delicate one with very 

 long rays, was found along the tide line of Brown Island and Minnesota 

 Reef. Amphiodia periercta was found only on the beach at Olga. It lies 

 buried in sand about 1.^ inches deep with only the tips of the rays exposed, 

 and these are drawn down when the animal is disturbed. Ophiura brevi- 

 spina and Gorcjonocephalus eucnemis (basket star), were found only in 

 deep water. 



Only i species of Echinoidea (sea urchins) were found. They are 

 not difficult to distinguish. Strongylocentrotus franciscanus and S. 

 drobachiensis are the most common. Only a few specimens of S. purpiira- 

 tus were found. Echin^rachnius edcentricus was abundant in the sand at 

 False Bay on the southwestern side of San Juan Island. 



Holothuroidea (sea cucumbers) were very numerous in nearly all 

 parts of the territory over which material was collected. Cucumaria japon- 

 ica was the most abundant along the tide line, and specially noticeable 

 on account of its brilliant color. C. chronhjelmi was found at the tide line 

 as well as in deep water. C. lubrica and C. pulcherrima are not common 

 and were not found except by trawling. Stichopus californicus was 

 abundant below low tide, specially in some bays. It is commonly much 

 noticed on account of its large size. 



Acknowledgments are due to Dr. N. Fasten, Dr. T. C. Frye, Prof. 

 T. C. D. Kincaid, Dr. S. C. Langdon and Prof. H. L. Osterud. all of the 

 University of Washington. 



Phylum Echinodermata 



KEY TO CLASSES 



A. With radial appendages or arms. 



B. Arms not sharply marked off from the disk ; ambulacral grooves 

 containing tube-feet present. asteroidea (p. 22) 



BB. Arms sharply marked off from the disk; ambulacral grooves and 

 tube-feet lacking. ophiitroidea (p. 33) 



AA. Without radial appendages or arms. 



C. With hard calcareous shell. echinoidea (p. 35) 

 CC. Without hard calcareous shell. holothuroidea (p. 36) 



