468 BULLETIN 120, UNITED STATES NATIONAL MUSEUM. 



Unfortunately no Opalinids are known from the great Amazon 

 Valley. 



In southern South America we find all genera, except, of course, 

 Oi^lma which is not found in America south of Panama. Of the 

 two Protoopalinae^ one, diplocarya^ is a relict of the most archaic 

 Equatorian group of species, and the other belongs to a group with 

 African affinities. It is interesting to find six Zelleriellae here in 

 the southern part of the continent, though they have but a single 

 known representative in eastern Brazil. Zelleriellae are abundant 

 in Central America, in northern and northwestern South America 

 and in southern South America, but not, so far as our data go, in 

 central South America. The Paraguayan Cepedea is a serious 

 puzzle, for it so closely resembles the Euro-Asian Cepedea dionidiata 

 as to be indistinguishable. We have called it a distinct subspecies 

 only because of its so distant habitat. 



The Eastern Hemisphere is sharply demarcated from the Western 

 Hemisphere by the absence of Zelleriella, except one species in Aus- 

 tralia and barely possibly another in "Asia," also by the absence of 

 narrow Opalinae, except one immigrant species from North America 

 and 0. virgula, of doubtful affinities. 



Palaearctica, in its Asian portion, shows four Protoopalinae, two 

 of them similar to European species, eight Cepedeae, two of which 

 show relationships to Malaysian forms, and six Opalinae all broad 

 except for one immigrant from America. Ceylon is not included. 



Europe and northern Africa show four Protoopalinae represent- 

 ing two ancient groups, five Cepedeae similar to northern Asian 

 forms, and two or three species of Opalinae^ one the narrow immi- 

 grant from America, the others O. ranaruin and the somewhat sim- 

 ilar O. cincta which might perhaps be regarded as a subspecies of 

 ranarum. The broad Opalinae are therefore dominantly Asian 

 rather than European. 



Southern and southeastern Asia and Malaysia give us four Protoo- 

 palinae of groups more modified than those in Europe, eight 

 Cepedeae^ including the most archaic and the most modified species, 

 also a single broad Opalina. 



Among the Australasian Opalinids we find in Papua only a single 

 very archaic Protoopalina. In Australia we find another species of 

 this most archaic group in the genus ProtoopaKna and seven other 

 species, all of little modified character except one {tenuis), which 

 shows close similarity to the elongated slender Malaysian P. -jiUformis. 

 There is known a single Australian species of Zelleriella closely simi- 

 lar to the American forms. No multinucleate Opalinids are in Aus- 

 tralia. 



From tropical and southern Africa we loiow seven Protoopalinae of 

 wide variety — one {xenopodos) belonging to the most archaic group 

 of all and one other {africana) approaching in form the very slender 



