﻿ASTROPIIYTON COSTOSUM. 



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ands, and at Charleston, S. C. It is fond of twining round Gorgonice, 

 in -which situation I have taken it on the mud fiats of Key West, just 

 below low-water-mark. When taken out of the water, it rolls up its 

 many branches compactly. Its color, when alive, is similar to that of 

 the alcoholic specimen, but is more brilliant, and the color of the back 

 is more decidedly purplish. 



It is very readily distinguished by the high radial ribs and their 

 coarse spines, the long, evenly branching arms, the absence of tentacle- 

 scales Avithin the margin of the disk, the position of the madrejioric 

 shield at the inner angle of the lower interbrachial space. 



The original "Astrojihyton costosum, cosiis conicis," &c., of Linck, is 

 not to be recognized as any species now known. Lamarck identified it 

 with A. ctrborescens, the Mediterranean species, and was followed in the 

 mistake by Agassiz. J. Miiller considered it the same as his A. muri- 

 cahim, and Avas equally Avrong. Seba gives an excellent plate of the 

 present species, and calls it Ash^ojjhyton costosum, Avhich name I have 

 kept, because it can be identified Avith certainty, and because it is 

 strictly binomial. 



In the Jardin des Plantes is the original of Euryale costosum of Lar 

 marck (not Seba), brought by Mauge, in 1799, from the Antilles. There 

 is a second specimen brought from Guadeloupe, in 1837, by Beauper- 

 tuis. What is most extraordinary, is, first, that this is neither the true 

 A. costosum {Euryale muricatum Lamk.), nor A. coecilia, nor A. Krehsii, 

 the only species of the Antilles Avhich the careful research of Dr. Liitken 

 has brought to light ; and, secondly, that this particular species bears so 

 close a resemblance to A. arborescens as readily to pass for it. If it 

 should really turn out to be a distinct species, it must receive a new 

 name, as that of costosum is already taken. 



LIST OF SPECIMENS. 



