560 



MEMOIRS OP THE CARNEGIE MUSEUM. 



Locnlities Represented in Carnegie Museum. — Rio Piracicaba, Silo Paulo, 

 Brazil (Von Ihering donor, authentic specimens). One complete shell and one 

 odd (left) valve. Rio Tiete, silty river banks, twentj^-five miles above Itapura, 

 Sao Paulo, Brazil (J. D. Haseman coll., September 27, 1908). Four specimens 

 with soft parts, one male and three females. Rio Tiete, Itapura, Sao Paulo, Brazil 

 (J. D. Haseman coll., September 28, 1908). Five specimens, one of them a male 

 with soft parts. 



Distribution. — Rio Tiete and Piracicaba of Upper Paranti-drainage in Sao 

 Paulo, Brazil. 



This species has been well described by Von Martens and Von Ihering, and I 

 do not need to add anything, except that the dimensions vary considerably, the 

 height from 71 to 86 pr. ct. and the diameter from 53 to 66 pr. ct. of the length. On 

 the average our specimens are more swollen than the previous measurements would 

 indicate. The most characteristic feature of this species is the quite unique de- 

 velopment of the rilis of the posterior slope, which are much stronger than the 

 oblique "wrinkles" often found in species of Diplodon. 



Simpson has put this species in the genus Castalina, but I do not see any 

 reason for this. The posterior slope undoubtedly has the characters of Castalia. 

 The species, indeed, stands isolated in the genus, and cannot be confounded with 

 the other species, and for this reason, probably. Yon Ihering omitted it in his key 



(1910). 



Measurements. 



Anatomy. — The soft parts of two males and three barren females arc at hand. 



A description has been previously given by myself (1911a, p. 117). However, 

 it should be added that in one female investigated the branchial opening is open 

 in front, but probably torn. In another, a male, it is undoubtedly open; this is 

 an old individual, the largest at hand, and here also it may be that it has been in- 

 jured during life. In the other three specimens (one male and two females), the 

 branchial opening is closed in front. According to Von Ihering (1891, p. 476), 

 this opening is closed in 80 pr. ct. of the cases. 



