SOME WEST INDIAN ECHINOIDS. 



17 



these specimens— though I should like to examine the specimen labeled SUreoc%- 

 daris ingolfiana. During my short stay at the U. S. National Museum I had to 

 use the time for investigations relating to my own special work. When I found ni 

 the collections of the museum specimens which were unnamed, or which I thought 

 evidently wrongly named, I put a label in the jars with the name I thought the 

 right one. But I had no time to spend for a more exact and entirely reliable iden- 

 tification. What has here happened is a warning that one should never trust 

 oneself to name a specimen without having examined it fully in regard to all its 

 characters. I venture to think that among the specimens really exammed in 

 detail by me, and not seen only in a cursory way in foreign museums, such errone- 

 ous identifications will not be found. 



Quite recently this matter has become somewhat more serious. Lambert 

 and Thiery, in their Notes echinologiques I, Sur le genre Cidaris," find in this 

 case an argument against the use of pedicellariaj in classification: "En negligeant 

 les caracteres du test, on s'expose a des erreurs de determination comme celles com- 

 mises d'apres H. L. Clark, par Mortensen, I'auteur de cette classification." I may 

 state here expressly that this case can in no way be taken as a proof against the 

 value of the pedicellarije; it is not the pedicellariaj which have led me to the false 

 determinations (as far as I can remember I did not even examme the pedicellaria 

 of tlic specimens of Phyllacanthus baculosa), but the fact that I did not examme 

 the specimens more closely. 



AR.S;OSOMA BELLI Mortensen. 

 Plate 11; plate 12, fig. 1. 

 Arxosoma belli Th. Mortensen, //ijo// Echinoidea, pt. 1, p. 54-55, pi. 12, fig. 29; pi. 13, figs. 

 10, 11, 22. 

 This species, of which a short preliminary description was given in the Irigolf 

 Echinoidea " 1 found represented by several specimens in the collection of the 

 U S National Museum (labeled Asthenosoma hystrix) . Having had some specimens 

 sent to Copenhagen, I am at length able to give a full description of the species 

 and to point out more clearly the afiinities with the real Arseosoma Jiystnx&nd 

 with A. femstraturn, as also with .4. violaceum, which has also hitherto not been 

 fully described or figured. A. belli is, moreover, perfectly recognizable from the 

 prchminary description, the pedicellari* being really very characteristic for this 



^^^""The specimens examined are from the Albatross stations 2350 (off Havana, 213 

 fathoms- 2 young specimens) and 2655 (north of the Bahamas, 338 fathoms; 2 

 large specimens) . In addition there is one specimen from Mayaguez Harbor, Porto 

 Rico 220-225 fathoms (the Fish Hawk Porto Rican expedition). The species 

 is as' vet knovvTi only from the West Indian seas (137-338 fathoms), not from the 

 European side of the Atlantic, in contrast to A. fenestraium, which occurs on 

 both sides of the Atlantic Ocean-at least I have been unable to distinguish the 



West Indian from the east Atlantic form from the mate rial at hand. 



^Bull. Soc. Sci. Nat. Haute^Marne, vol. bTmg, p. 24. » Pt. 1, pp. 54-55. 



