1898.] NATURAL SCIENCES OF PHILADELPHIA. 107 



place. From Sorocaba, Ypanema, etc. I have received B. ovalus, 

 but in Piracicaba and St. Rita in the western zone we have B. 

 oblongus, which is evidently an immigrant from Paraguay, Bolivia, 

 etc. with many of our other Bulimus and Helix. 



The same conditions are noticed in other land shells. We find 

 identity of species from Bahia with those of the La Plata and Rio 

 Grande do Sul, which are absent from St. Catharina northward on 

 the littoral. 5 



I believe finally it is time for European naturalists to take notice of 

 these studies. It is quite an unscientific method, to continue to con- 

 sider the neotropical region as a natural unity zoologically. This 

 region in later secondary and early tertiary time was formed by 

 coalescence of an Antarctic and a tropical element, the latter having 

 been in mesozoic time connected with Africa. It was only with 

 the pliocene period 6 a connection with North and Central America 

 was formed. The ancient West Indian bridge being only during 

 pleistocene time replaced by the present Isthmus of Panama. 



We know to-day the history of the South American mammals, 

 being able to separate the ancient endemic element from the pliocene 



5 My various papers referring to the distribution of the Brazilian fauna and 

 to the history of the neotropical region are as follows. The last three treat 

 of the subject more fully: 



Kevision der von Spix in Brasilien gesammelten Najaden. Arch. f. Naturg. 



1890, p. 117-170. Taf. IX. 



On the ancient relations between New Zealand and South America. Trans, 

 of the New Zealand Instit, Vol. XXIV, 1891, p. 431-445, (cf. Ausland, 



1891, No. 18). 



Die geographische Verbreitung der Flussmuscheln. '• Ausland," Stuttgart, 

 1890, No. 48 and 49 cf. The New Zealand Journal of Science, 1891, p. 151. 



Die geographische Verbreitung der Ampullarien in siidlichen Brasilien. 

 Nachrbl. d. Deutch. Malak. Ges., No. 5 and 6, 1891. 



Anodonta und Glabaris. Zoolog. Anzeiger, No. 380-381, 1891-92. 



Ueber die Beziehungen der chilenischen und siidbrasilianischen Siisswas- 

 serfauna. Verhandl. d. deutschen wissensch. Vereines zu Santiago, 1891, II. 

 Bd., p. 143-149. 



Morphologie und Systematik des Genitalapparates von Helix. Zeitschr. f. 

 wissensch. Zool., Bd. 54, 1892, p. 386-520, Taf. 18-19 (cf. p. 489, Geograph. 

 Verbreitung). 



Das neotropisch Florengebiet und seine Geschichte. Botan. Jahrbiicher. 

 Engler. Bd. 17, 1893, p. 1-54. 



Najaden von Sao Paulo und die geographische Verbreitung der Siisswasser- 

 faunen von Siidamerika. Archiv. f. Naturgesch., 1893, p. 45-140, Taf. Ill and 



IV - 



Die Ameisen von Rio Grande do Sul. Berliner Entomolog. Zeitschr. Bd. 



39, 1894, p. 321-446. 



6 And if in contrast to my opinion Ameghino is right, there was a connection 

 also in the beginning of the tertiary period, followed without doubt by a long 

 time of separation of both Americas. 



