ortmann: south American naiades. 



485 



The essential eliaracter of this group is in the beak-sculpture, which, however, 

 is very variable, although the granular structure is always more or less evident. 

 It is hardly i)os8ible to give any additional characters, except that the hinge- 

 teeth are moderately developed, subcomi)ressed, and hardly ever stumpy. Two 

 pseudocardinals are in each valve, but sometimes there are reductions. 



I have very little material representing this group. The soft parts of only 

 two specimens are at hand, one too young to be of any value, the other a male. 

 Thus nothing can be said about the structure of the female. All my specimens 

 seem to belong to one species, which is very variable, and has a very limited range 

 in the coastal streams of eastern Brazil. 



The genetic connections of this group likewise caimot be properly ascertained. 

 The beak-sculpture does not seem to be very primitive, when compared with the 

 other species of the genus. In the shape of the shell and the hinge, there is simi- 

 larity to the next group (chilensis), which possibly may be the most primitive of 

 the genus. 



5. DiPLODON GRANOSUS (Bruguiere) (1792). 



Compare: Unio tnultistn'atus Lea, Von Ihering, 1890, p. 165. 

 Unio psammactimis Bronn, Von Ihering, 1893, p. 107. 

 Diplodon expansus Von Ihering, 1910, p. 134. 

 Diplodon granosus (Brugiere), Simpson, 1914, p. 1250. 



I am inclined to accept the earlier opinion of Von Ihering (1890), and that of 

 Simpson, that a number of so-called "species," of which Simpson has given a full 

 synonymy, belong here. Possibly several others should be included. 



Type-locality. — Brazil and Guiana. 



Additional Localities. — Rio de Janeiro (psommactinus, Philippi) (Von Ihering) ; 

 coastal streams in eastern Brazil, between Rio de Janeiro and Bahia, but not to 

 the south of Rio (Von Ihering); Rio Negro, Prov. Rio de Janeiro, Distr. St. Rita 

 (Bunker's coriacem, Von Ihering); Tayuara, Distr. Canta Gallo. Prov. Rio de 

 Janeiro (Von Ihering); Rio Parahyba do Sul, Rio de Janeiro (Von Ihering); Nova 

 Friburgo, Rio de Janeiro (Von Ihering). Rio Paraguassu, Bahia (Von Ihering, 

 1910, p. 139, as nmUistriatus Lea). Rio Doce, Espirito Santo (Von Ihering, 1910, 

 p. 134, as expansus Kuester). 



Neio Localities. — Mountain creek, Raiz da Serra, near Santos, Sao Paulo, 

 Brazil (J. D. Haseman coll., July 26. 1908). One specimen with soft parts, male. 

 Rio Ribeira, Iporanga, Sao Paulo, Brazil (J. D. Haseman coll., December 1. 1908). 

 Two specimens, young, one with soft parts of the male type. 



X^rt 







