298 Verrill, Notes on Radlata. 



short spines of the upper sui'face are light green, with narrow purple 

 bands. 



In life, according to Mr. Bradley's observations, the spots along 

 each side of the interambulacral zones are bright blue and very 

 conspicuous. 



Panama and Pearl Islands ;* one specimen was found on the reef at 

 low-water, the others were dredged in four or five fathoms, on shelly 

 bottom, — F. H. Bradley. 



This sjjecies has probably been confounded, hitherto, with A. radiata 

 of the Indian Ocean, at Zanzibai*, etc., to which it is closely allied. 



Echinocidaris Stellata (Blainv. sp.) Agassiz and Des., Catal. Rais., 1846. 



Echinocidaris incisa A. Agassiz, Bulletin Mus. Comp. Zoology, No. 2, p. 20, 1863. 

 Echinocidaris longispina Lutken, Bidrag tQ Kundskab om Echiniderne, p. 62, Vidensk. 

 Meddelelser, p. 130, 1864. 



A large number of specimens of this species, of various sizes, were 

 collected by Mr. Bradley at Panama and the Pearl Islands, where 

 they occur at low-water mark on the reef, among stones and in crev- 

 ices. At Zon-itos, Peru, he obtained many specimens of large size, 

 and, also, a few from La Union, San Salvador. From the Essex Insti- 

 tute we have a specimen from Margarita Bay, Lower California. It 

 also occurs at the Galapago Islands (Agassiz and Desor), and at 

 Guayamas (A. Agassiz), and Realejo (Dr. Ltltken). Mr. Bradley ob- 

 tained one living specimen at Paita, Peru. 



The specimens described by Mr. A. Agassiz were not fully grown, 

 and differ in some respects from larger ones. 



A specimen from Zorritos, measuring six inches in diameter, in- 

 cluding the spines, has spines two inches in length ; others have 

 somewhat shorter spines. The spines near the center of the upper 

 surface are quite short, but increase rapidly in length toward the 

 periphery, where they are longest, round, moderately slender, gradu- 

 ally tapering. On the lower side they diminish rapidly in size and 

 length and have flattened tips ; around the actinal ai-ea they are 

 quite small. 



A specimen having the test 2-1 inches in diameter, and 1-35 high, 

 has the actinal opening 1 inch in diameter ; the anal area -3 ; from 

 the outside of an ocular plate to the oiiter point of the opposite geni- 

 tal plate -6 ; length of genital plates -22 ; greatest width -2 ; breadth 

 of ambulacral zones at periphery "42 ; of interambulacra '85. Test 

 usually regularly arched above, often a little depressed. 



The genital plates are large, pointed outwardly, and project into 

 the interambulacra so as to form a very distinct star ; inwardly their 



* More recently sent by J. Pedersen from the Gulf of California, near La Paz, — Reprint. 



