54 THE NAUTILUS. 



Habitat: Clinch and Holston rivers. 



The examples figured had been labeled Unio cicatricosus by Dr. 

 James Lewis, and his determination had been O. K.'d by Mr. C. T. 

 Simpson. Shells the same as these have been loaned the writer by 

 Mr. W. A. Marsh under the same name (i. e., varicosus). Others 

 of the same species had been given the writer by Mr. Bryant 

 Walker as being the varicosus of Lea. With their attention called 

 more carefully to the shell, however, both of these gentlemen now 

 concur with me as to their novelty. Type in my collection. This 

 shell is remotely, if at all, related to the other shells above men- 

 tioned. There is apparently a slight relationship to Unio propinquus 

 in its general facies, but the species is in reality very distinct. 



NOTE The term Unio is used above in the old broad sense of 

 denoting a naiad shell having both lateral and cardinal teeth, and 

 not in the restricted sense now held by our modern conchologists, 

 and so embraces the various divisions of Quadrula, Pleurobema, Ple- 

 thobasis, etc., etc., as the future study of the soft parts may incline 

 the future systematists to place them. 



COEKESPONDENCE FROM BRAZIL. 



BY FRED. BAKER. 



S. S. RHAETIA, HAMBURG-AMERICA LINE, 

 ON THE Rio NEGRO, 950 MILES FROM THE MOUTH 



OF THE AMAZON, July 24, 1911. 

 Dear Dr. Pilsbry : 



This goes in compliance with my promise to report of our progress. 

 We left Natal, in the State of Rio Grande do Norte, on July 1st for 

 Pard, after a stay that was comparatively barren of results zoologic- 

 ally. The reptilian collection is good, but in all other lines the 

 number of species is small. My collection of marine shells not- 

 withstanding several days spent in dredging is small enough, so that 

 I feel sure that they are not to be found on this immediate coast, for 

 reasons that we can only guess at at present. By interesting the 

 ubiquitous small boy in a couple of interior towns I was able to secure 

 several thousand land and fresh-water shells of a rather limited num- 

 ber of species. I feel reasonably sure that I have two new species 



