l68 ECHINOIDEA. I. 



families, they cannot be said to correspond very exactly to each other. Echinus margaritaceus and 

 elegans must be referred to two different genera, Stcrcchinus and Echinus, so that these species can 

 not be placed as substitutes for each other either. Upon the whole it is worthy of notice that it 

 proves necessary to refer all the antarctic EC himis^ -species to another genus {Stercchinus} than the 

 northern species. It seems to be rather gratuitous to place the separate species of these two genera 

 against each other as substitutes. With regard finally to Strongylocentrotus drobachicnsis and albus, 

 they, to be sure, have some resemblance as to habitus -- nevertheless they belong to two different 

 families. - - With this I suppose it to be sufficiently proved that there is no special resemblance 

 between the arctic-subarctic and the antarctic-subantarctic Echinid-fauna. 



