While no definite conclusions can be dra\\n I'rom the few hirv;e ol' I lo- 

 lothurians hitherto known, and likewise tin- (irinoids are out ol ((iii'slioii 

 in this connection having no true pelagic larv.e. the Ophinroid larva. 1 have 

 an imporlanl bearing on the problem. Larva 1 belonging to the genera 

 Ophiolhri.i, Ophiopnolis, Ophiitclis and Ainphiuni arc known but only one 

 of eacli genus. They do not afford so very characteristic dillerem rs ;is 

 one should expect, since they belong to three dilTerenl families, and 

 those of Ophioplwlis and Ophiddis are more dilTerenl than should be 

 expected afler the apparently near relation of these I wo genera . Then 

 within the genus Ophiuni we know with certainly the larva- of the two 

 species Oph. albidn and Ir.iluniltt. and thesi- are so dilTerent I hat one- would 

 rather think they must belong to dilTerenl families. The larva- which are 

 with a considerable degree of probability referred to ()j>h. ////i/i/.s and 

 Honitilophiura </di(ld (Koehler) again are very dilTerenl from each other 

 as well as from the two named above. These fads are thus decidedly 

 opposed to the conclusions to be drawn from our previous knowledge of 

 the Echinoid and Asteroid larva-. Considering, however, that our knowledge 

 of the natural affinities of the vast number of Ophiurids is still rather 

 unsatisfactory, even in spile of tin- more recent attempt at a natural 

 classification of this group by Malsumolo, it seems to me- that the 

 facts known of the Echinoid and Asteroid larva- outweigh those of the 

 Ophinroid larva-, and lead to the conclusion that these larva 1 , on the con- 

 trary, lend to prove that there is something wrong with our classification 

 of the Ophiuroids. 



In spile of these O/;/f/;;n/-larva' it seemed then a legitimate conclusion thai 

 the Kchinoderm larva- are really of considerable classificalory value. Ihe 

 larva? of nearly related forms agreeing in I heir main characters; the opposite 

 conclusion would then be equally legitimate, that when the larva- of two 

 forms, apparently nearly related, prove to be essentially dilTerent, those 

 forms are not in reality nearly related. The study of the larval forms will 

 then a fiord a very imporlanl lest for the value of our classification of 

 the adult forms. 



It is evident that the knowledge of a very much larger number of 

 Kehinoderm larva 1 lhan Ihe comparatively few known (ill now is required 

 lor placing the idea of the classificalory value of these larva- on a more 

 firm base. Nearly all the researches hitherto made on the development 

 and the larval forms of Echinoderms were carried <ml on species occurring 

 in the European and North American Seas, only a few forms I'rom the 

 tropical seas of America having more recently been made the object of 

 study (Tennenl). Mill, moreover, il is mainly a few selected types 

 which have, over and over again, been studied, so that even of the com- 



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