164 NATURAL HISTORY BULLETIN 



When picked up on the beaches, or when poorly preserved, its 

 appearance is much altered, aside from its ordinary variations, 

 which are considerable. 



On the other hand, the A. duplicatus of Gray, as determined 

 by Perrier, after an examination of the types, is the same as 

 A. variabilis Liitken. It is characterized by the presence of a 

 double row of superomarginal spines, largest proximally, and is, 

 in fact, the most spinose species of the West Indian fauna, and 

 therefore quite unlike the figure by Agassiz. 



For the same reason reference of Gray's (well named) A. 

 dubius to A. duplicatus is evidently wrong, for Gray placed it in 

 his group having no superomarginal spines. It may well be 

 merely the not uncommon variety of A. articulatiis in which the 

 small superomarginal spines are obsolete or undeveloped. 



Perrier stated, 1875, that he had examined cotypes of Liitken 's 

 species. He also states that in some of his specimens the upper 

 marginal plates were entirely destitute of spines. 



This species is common on sandy bottoms, in shallow waters, 

 on the southeastern coasts of the United States, from Beaufort, 

 N. C, to the Florida Keys, and on the western coast of Florida, 

 north to Egmont Key and Tampa Bay. 



It has been stated by A. Agassiz that it has been found on the 

 coast of southern New Jersey, but I have seen none from that 

 district. It needs confirmation. It ranges to Yucatan (Ives), 

 and from the Bahamas to the Lesser Antilles. Dominica I. (A. 

 H. Verrill). Many West Indian localities are doubtful because 

 several authors have confused this with other species. Kingston 

 Harbor, Jamaica, near Port Royal, in very shallow water on 

 sandy bottoms, near or among mangroves (H. L. Clark). West 

 Florida, near St. Martine Reef (U. S. Nat. Mus.). 



Taken by the U. S. Fish Commission, at several stations off 

 the Carolina coasts and Cape Hatteras, as far north as 35° 42' N. 

 lat. It occurred there in 4 to 43 fathoms, 1883 to 1885. Also off 

 W. Florida, 27 to 88 fathoms. 



It was taken by the Bahama Expedition, on the Great Bahama 

 Bank, in shallow water. The Yale Museum has specimens from 

 Egmont Key, W. Florida (W. T. Coons, No. 2213). 



