526 CLARK 



Ophiothrix magnifica Lyman. 



A western Central American species. 



The brittle star which Liitken and Mortensen describe under the 

 name Ophiothrix galapagensis seems to be, without much doubt, the 

 young of O. spiculata. 



ECHINOIDEA. 



Cidaris thouarsii Valenciennes. 



This species, common from Guayamas to Panama and the Pearl 

 Islands, and previously known from the Galapagos, is represented in 

 the collection by 1 7 specimens, 1 1 dry ones from Tagus Cove, i small 

 one from Narboro, and 5 alcoholics from Iguana Cove. 

 Diadema mexicanum A. Agassiz. 



The collection contains 4 dry specimens, all from Tagus Cove, the 

 largest 100 mm. in diameter and 48 high. Previously known from 

 the Pacific coast from Acapulco to Puget Sound. 

 Strongylocentrotus gibbosus (Valenciennes) . 



There are 1 1 dry specimens of this interesting urchin, from Tagus 

 Cove. They range in diameter from 16 to 40 mm. The color is a dis- 

 tinct reddish-brown, the spines very dark olive, tipped with purplish; 

 specimens from Chile and Peru, whence the species was previously 

 known, are said to be gray. All but the smallest of the shells before 

 me are distorted by the presence of the parasitic crab so generally found 

 in this urchin, and in all but 3 the crab is present. This species has 

 been previously reported from the Galapagos. 

 Toxopneustes semituberculatus (Valenciennes). 



There are 4 dry specimens from Tagus Cove, and 8 alcoholics from 

 Iguana Cove, ranging in diameter from 27 to 50 mm. They agree well 

 with Agassiz's description except in color; the test is light brownish- 

 green, the numerous pedicellariae purple and the spines bright yel- 

 lowish-green, less yellow in alcoholic specimens. Previously recorded 

 from Cape San Lucas, Central America and the Galapagos. 



Hipponoe depressa A. Agassiz. 



There is a single fine specimen of this species, 118 mm. in diameter, 

 from Tagus Cove. Previously reported from the Gulf of California 

 and west coast of Central America. 

 Clypeaster rotundus A. Agassiz. 



There are 5 very handsome dry specimens in the collection, dredged 

 in 50 feet of water in Tagus Cove. All are dull purple in color, but 

 differ considerably in shape; one is 160 x 135 mm. while another is 

 145 X 138 mm., the largest is 162 x 150 mm. They are easily dis- 



