l68 ECHINOIDEA. I. 



families, they caiinot be said to correspond very exactl}- to each otlier. Ecliinus margaritaceus and 

 clegans must be referred to two differeiit genera, Stcrrchimis and Echiinis, so that these species can 

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

 proves necessary to refer all the antarctic <.Echi)iiis -ST^ecies to another genus (Sfrrcr/ii/z/ts) than the 

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

 against each otlier as substitutes. With regard finally to Strongyloccntrotus drobacJiicnsis and albiis, 

 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. 



