1913.] NATURAL SCIENCES OF PHILADELPHIA. 623 



Three genera represented in the first and second districts: 

 Oxystyla, Physa, Planorbis. 



Six genera represented in the second and third districts: Anodon- 

 tites, Castalia, Corona, Euglandina, Happia, Leptinaria. 



Two genera represented in the first and third districts: Helicina, 

 Streptaxis. 



Thirty-seven species and subspecies were taken in the first district 

 only; thirtj^-six species and subspecies from the second district 

 only; twenty-two subspecies from the third district only. 

 Four species were taken in all three districts. 

 Six species in the first and second districts ; six species were found 

 common to the second and third districts, and two species to the 

 first and third districts. As the collections are very incomplete, 

 it is not necessary to list the species taken in each district here, 

 but the degree of endemicity is roughly indicated by this summary. 

 A list of the locations from which the collection was taken, with 

 the latitude and longitude figured for some of the less known places 

 as accurately as it could be done from the ordinary maps, is published 

 on succeeding pages. 



In conclusion, I wish to acknowledge my great obligation to 

 Dr. Branner for inviting me to become a member of the Expedition 

 and to the other members of the party for many kindnesses; to 

 Professor F. W. Kelsey, of San Diego, California, who has prepared 

 all the photographs used in the reproductions for this paper; to 

 Dr. H. von Ihering, of Sao Paulo, Brazil, for furnishing valuable 

 papers on Brazilian moUusks; to Dr. Paul Bartsch of the National 

 Museum for comparing doubtful species of the Ampullariidce with the 

 collections of that institution, and in largest measure to Dr. H. A. 

 ' Pilsbry, of the Academy of Natural Sciences of Philadelphia, for a 

 very large amount of help in the determination of species of all 

 groups and for most valuable assistance in the preparation of this 

 paper. 



Locations of Stations Mentioned in this Paper. 



Natal, Lat. 5° 50' S., Long. 35° 30' W. 

 Pirangy, about 20 miles down the coast from Natal. 

 Paparj', about 30 miles southerly from Natal. 

 Estremoz, Central R. R., 17 kilometers from Natal. 

 Ceara-Mirim, Central R. R., 34 kilometers from Natal. 

 Taipu, Central R. R., 56 kilometers from Natal. 

 Baixa Verde, Central R. R., 84 kilometers from Natal. Present 

 terminus of railroad. 



