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type witlioiil a typical pelagic larva, the Comatulids thus ofTering a case 

 analogous to that of the Denthochirole Hololhuiians. It may perhaps be 

 expeclcd Ihal lypical pehigic Iarv;e will be found to exist in some of the 

 stalked Ciinoiils; but till now iiolhing is known about thai, and accord- 

 ingly the Crinoids do not contribute to the solution of the problem here 

 discussed ami iiiusl hv left out of consideration for Ihe i)resenl. 



After this summary review we may state as the result of these researches 

 that the facts hitherto brought to light are decidedly in favour 



f t h e V i e w I h a t t h e 1 a r \' se o f t h e 1^ chin o d e r m s h a v e a n i m p o r t a n t 

 bearing on the classification of the adult forms. It seems a suf- 

 ficiently established fad I hat the larvae of closely related species are upon 

 the whole very much like one another, often hardly distinguishable, and, 

 further. Ilia I the larva* of allied genera agree in important characters, so 

 thai we gel groups of larva\ larval "families", "'orders", corresponding lo 

 Ihe groups (families, orders) of the adult forms. Accordingly the very im- 

 portant conclusion seems justified, that when forms, which were sup- 

 |)()se(l lo be nearly related, i)rovc lo have essentially different 

 larvae, these forms are not in reality nearly rehiU-d'). The study 

 of the Iarv<T will thus form a most important criterion for our classifica- 

 tion, giving, so to say, the final judgment of its true value, and we are 

 justified in slating that no classification which is i n contradiction 

 to the evidence given by the larvae can give an adequate expres- 

 sion of the natural relationship of the adults. — These results 

 probably apply also to other animal groups than the Kchinoderms; but 

 this side of the problem will not be discussed on Ihe present occasion. 



Although the facts already known seem to warrant the above conclu- 

 sions. I would maintain most emphatically that the present researches are 

 only to be regarded as a reconnaissance in this field. Proof is given that 

 the way entered upon is the right way, and we nun be sure that further 

 researches will yield imporlanl results. Hut there is a long way to go. Wiinl 

 has been obtained as yet is nothing more than random samples, taken here 

 and there. It must be claimed thai all the various forms should be 

 studied, and not only the genera; it will be equally important 

 to have all the species within the various genera made the object 



01 study, even though Ihey are, apparently or really, ever so closely 

 related, and il is equally desirable that the larva* should be studied and 

 figured alive. Thus we will gradually acquire a sum of knowledge of the 

 greatest importance for reaching the end of all systematic work, the com- 

 prehension of the multitude of living forms in their natural relationshij). 



') Provided, of course, their cinbryological conditions be tlic same. Tliat closely related 

 species may differ in one haviiif^ typical larv;c. Ihe other having abbreviated development or 

 being viviparous, is quite a dilTerenl Ihina. and does not interfere wilh llie above conclusion. 



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