130 Bulletin, Vanderbilt Marine Museum, Vol. IV 



Material examined : One large specimen collected at Port Tanamo, 

 north coast of Cuba, 2 fms., January 23, 1924, Cat. no. 263. Two 

 very young specimens from the same locality, Cat. no. 264. One 

 large specimen from Dry Tortugas, Florida, Cat. no. 272. 



Color: The West Indian form of this species has both the test 

 and spines deep violaceous black in the larger adults, but in the 

 younger adults the slender spines are alternately cross-banded with 

 creamy or yellowish and purple. 



Dr. H. L. Clark presents most interesting data on the color varia- 

 tion found in this species in the Indo-Pacific, in his "Echinoderm 

 Fauna of Torres Strait," p. 146, also in his "Catalog of the Recent 

 Sea Urchins." 



Life history: This species has been studied and reported by Dr. 

 Mortensen. 



Technical description : Adult specimens may attain a test diam- 

 eter of three to three and one-half inches, with spines six inches 

 long. The test is moderately thin, flattened at both poles. The am- 

 bulacral region has the tubercles arranged in two vertical rows ; these 

 tubercles are somewhat smaller than those of the interambulacral 

 region. The ambulacra are narrower abactinally than at the ambitus, 

 with few or no tubercles above the midzone. The tubercles of both 

 areas are crenulate and perforate. The poriferous zones are narrow 

 with the pores arranged in simple pairs forming arcs around the adja- 

 cent tubercles. The primary spines are long, three to six inches, slen- 

 der, hollow, black, finely verticillate. The three types of pedicellariae 

 found are illustrated. 



Nomenclature : I have followed the precedent of Dr. H. L. Clark 

 (1925), in using Diadema Gray, 1825, and Diadematidae Peters, for 

 this urchin, instead of Centrechinus Jackson, 1912, and Centrichinidae 

 Jackson, the correct names, for the reasons stated by Dr. Clark, who 

 deferred to such authorities as Mortensen and Bather, who had pro- 

 posed to continue the use of Diadema and Diadematidae and to secure 

 these a place on the list of Nomina Conservanda authorized by the 

 International Congress of Zoologists. Search of the opinions rendered 

 by the Congress, 1924 to June, 1931, fails to show any action taken 

 on this question. 

 References : Echinometra setosa Leske, Add. ad Klein, p. 100, 1778, 



tab. 37, figs. 1 and 2. 

 Diadema setosa Gray, Ann. Phil., vol. X, p. 4, 1825. 



